diff --git a/nvpy/nvpy.py b/nvpy/nvpy.py
index 8c680a7..e053852 100644
--- a/nvpy/nvpy.py
+++ b/nvpy/nvpy.py
@@ -44,6 +44,7 @@
 import re
 import collections
 
+import tk
 from utils import KeyValueObject, SubjectMixin
 import view
 import webbrowser
@@ -327,66 +328,70 @@ def __init__(self, config):
         # create the interface
         self.view = view.View(self.config, self.notes_list_model)
 
-        # read our database of notes into memory
-        # and sync with simplenote.
         try:
-            self.notes_db = NotesDB(self.config)
-
-        except ReadError, e:
-            emsg = "Please check nvpy.log.\n" + str(e)
-            self.view.show_error('Sync error', emsg)
-            exit(1)
-
-        self.notes_db.add_observer('synced:note', self.observer_notes_db_synced_note)
-        self.notes_db.add_observer('change:note-status', self.observer_notes_db_change_note_status)
-
-        if self.config.simplenote_sync:
-            self.notes_db.add_observer('progress:sync_full', self.observer_notes_db_sync_full)
-            self.notes_db.add_observer('error:sync_full', self.observer_notes_db_error_sync_full)
-            self.notes_db.add_observer('complete:sync_full', self.observer_notes_db_complete_sync_full)
-
-        # we want to be notified when the user does stuff
-        self.view.add_observer('click:notelink',
-                self.observer_view_click_notelink)
-        self.view.add_observer('delete:note', self.observer_view_delete_note)
-        self.view.add_observer('select:note', self.observer_view_select_note)
-        self.view.add_observer('change:entry', self.observer_view_change_entry)
-        self.view.add_observer('change:text', self.observer_view_change_text)
-        self.view.add_observer('change:pinned', self.observer_view_change_pinned)
-        self.view.add_observer('create:note', self.observer_view_create_note)
-        self.view.add_observer('keep:house', self.observer_view_keep_house)
-        self.view.add_observer('command:markdown', self.observer_view_markdown)
-        self.view.add_observer('command:rest', self.observer_view_rest)
-        self.view.add_observer('delete:tag', self.observer_view_delete_tag)
-        self.view.add_observer('add:tag', self.observer_view_add_tag)
-
-        if self.config.simplenote_sync:
-            self.view.add_observer('command:sync_full', lambda v, et, e: self.sync_full())
-            self.view.add_observer('command:sync_current_note', self.observer_view_sync_current_note)
-
-        self.view.add_observer('close', self.observer_view_close)
-
-        # setup UI to reflect our search mode and case sensitivity
-        self.view.set_cs(self.config.case_sensitive, silent=True)
-        self.view.set_search_mode(self.config.search_mode, silent=True)
-
-        self.view.add_observer('change:cs', self.observer_view_change_cs)
-        self.view.add_observer('change:search_mode', self.observer_view_change_search_mode)
-
-        # nn is a list of (key, note) objects
-        nn, match_regexp, active_notes = self.notes_db.filter_notes()
-        # this will trigger the list_change event
-        self.notes_list_model.set_list(nn)
-        self.notes_list_model.match_regexp = match_regexp
-        self.view.set_note_tally(len(nn), active_notes, len(self.notes_db.notes))
+            # read our database of notes into memory
+            # and sync with simplenote.
+            try:
+                self.notes_db = NotesDB(self.config)
+            except ReadError, e:
+                emsg = "Please check nvpy.log.\n" + str(e)
+                self.view.show_error('Sync error', emsg)
+                exit(1)
+
+            self.notes_db.add_observer('synced:note', self.observer_notes_db_synced_note)
+            self.notes_db.add_observer('change:note-status', self.observer_notes_db_change_note_status)
+
+            if self.config.simplenote_sync:
+                self.notes_db.add_observer('progress:sync_full', self.observer_notes_db_sync_full)
+                self.notes_db.add_observer('error:sync_full', self.observer_notes_db_error_sync_full)
+                self.notes_db.add_observer('complete:sync_full', self.observer_notes_db_complete_sync_full)
+
+            # we want to be notified when the user does stuff
+            self.view.add_observer('click:notelink',
+                    self.observer_view_click_notelink)
+            self.view.add_observer('delete:note', self.observer_view_delete_note)
+            self.view.add_observer('select:note', self.observer_view_select_note)
+            self.view.add_observer('change:entry', self.observer_view_change_entry)
+            self.view.add_observer('change:text', self.observer_view_change_text)
+            self.view.add_observer('change:pinned', self.observer_view_change_pinned)
+            self.view.add_observer('create:note', self.observer_view_create_note)
+            self.view.add_observer('keep:house', self.observer_view_keep_house)
+            self.view.add_observer('command:markdown', self.observer_view_markdown)
+            self.view.add_observer('command:rest', self.observer_view_rest)
+            self.view.add_observer('delete:tag', self.observer_view_delete_tag)
+            self.view.add_observer('add:tag', self.observer_view_add_tag)
+
+            if self.config.simplenote_sync:
+                self.view.add_observer('command:sync_full', lambda v, et, e: self.sync_full())
+                self.view.add_observer('command:sync_current_note', self.observer_view_sync_current_note)
+
+            self.view.add_observer('close', self.observer_view_close)
+
+            # setup UI to reflect our search mode and case sensitivity
+            self.view.set_cs(self.config.case_sensitive, silent=True)
+            self.view.set_search_mode(self.config.search_mode, silent=True)
+
+            self.view.add_observer('change:cs', self.observer_view_change_cs)
+            self.view.add_observer('change:search_mode', self.observer_view_change_search_mode)
+
+            # nn is a list of (key, note) objects
+            nn, match_regexp, active_notes = self.notes_db.filter_notes()
+            # this will trigger the list_change event
+            self.notes_list_model.set_list(nn)
+            self.notes_list_model.match_regexp = match_regexp
+            self.view.set_note_tally(len(nn), active_notes, len(self.notes_db.notes))
+
+            # we'll use this to keep track of the currently selected note
+            # we only use idx, because key could change from right under us.
+            self.selected_note_key = None
+            self.view.select_note(0)
 
-        # we'll use this to keep track of the currently selected note
-        # we only use idx, because key could change from right under us.
-        self.selected_note_key = None
-        self.view.select_note(0)
-
-        if self.config.simplenote_sync:
-            self.view.after(0, self.sync_full)
+            if self.config.simplenote_sync:
+                self.view.after(0, self.sync_full)
+        except BaseException:
+            # Initialization failed.  Stop all timers.
+            self.view.cancel_timers()
+            raise
 
     def main_loop(self):
         if not self.config.files_read:
@@ -404,7 +409,11 @@ def poll_notifies():
             self.notes_db.handle_notifies()
 
         self.view.after(0, poll_notifies)
-        self.view.main_loop()
+        try:
+            self.view.main_loop()
+        finally:
+            # Cancel all timers before stop this program.
+            self.view.cancel_timers()
 
     def observer_notes_db_change_note_status(self, notes_db, evt_type, evt):
         skey = self.selected_note_key
@@ -855,8 +864,14 @@ def main():
 
     config = Config(appdir_full_path)
 
-    controller = Controller(config)
-    controller.main_loop()
+    try:
+        controller = Controller(config)
+        controller.main_loop()
+    except tk.Ucs4NotSupportedError as e:
+        logging.error(str(e))
+        import tkMessageBox
+        tkMessageBox.showerror('UCS-4 not supported', str(e))
+        raise
 
 
 if __name__ == '__main__':
diff --git a/nvpy/tk.py b/nvpy/tk.py
index 48f1b79..4262b0a 100644
--- a/nvpy/tk.py
+++ b/nvpy/tk.py
@@ -1,10 +1,53 @@
-# nvPY: cross-platform note-taking app with simplenote syncing
-# copyright 2012 by Charl P. Botha <cpbotha@vxlabs.com>
-# new BSD license
-
-# Tkinter and ttk documentation recommend pulling all symbols into client
-# module namespace. I don't like that, so first pulling into this module
-# tk, then can use tk.whatever in main module.
-
-from Tkinter import *
-from ttk import *
+# nvPY: cross-platform note-taking app with simplenote syncing
+# copyright 2012 by Charl P. Botha <cpbotha@vxlabs.com>
+# new BSD license
+
+# Tkinter and ttk documentation recommend pulling all symbols into client
+# module namespace. I don't like that, so first pulling into this module
+# tk, then can use tk.whatever in main module.
+
+from Tkinter import *
+from ttk import *
+
+
+class Ucs4NotSupportedError(BaseException):
+    def __init__(self, char):
+        self.char = char
+
+    def __str__(self):
+        return (
+            'non-BMP character {} is not supported.  '
+            'Please rebuild python interpreter and libraries with UCS-4 support.  '
+            'See https://github.com/cpbotha/nvpy/blob/master/docs/ucs-4.rst'
+        ).format(self.char)
+
+
+def with_ucs4_error_handling(fn):
+    """ Catch the non-BMP character error and reraise the Ucs4NotSupportedError. """
+    import functools
+
+    @functools.wraps(fn)
+    def wrapper(*args, **kwargs):
+        try:
+            return fn(*args, **kwargs)
+        except TclError as e:
+            import re
+            result = re.match(r'character (U\+[0-9a-f]+) is above the range \(U\+0000-U\+FFFF\) allowed by Tcl', str(e))
+            if result:
+                char = result.group(1)
+                raise Ucs4NotSupportedError(char)
+            raise
+
+    return wrapper
+
+
+########################################################################
+# Apply the monkey patches for convert TclError to Ucs4NotSupportedError
+
+_Text = Text
+
+
+class Text(_Text):
+    @with_ucs4_error_handling
+    def insert(self, *args, **kwargs):
+        return _Text.insert(self, *args, **kwargs)
diff --git a/nvpy/utils.py b/nvpy/utils.py
index e000750..f245e29 100644
--- a/nvpy/utils.py
+++ b/nvpy/utils.py
@@ -10,6 +10,8 @@
 import threading
 from Queue import Queue, Empty as QueueEmpty
 
+import tk
+
 # first line with non-whitespace should be the title
 note_title_re = re.compile('\s*(.*)\n?')
 
@@ -202,6 +204,7 @@ def __init__(self):
 
     def add_observer(self, evt_type, o):
         from .debug import wrap_buggy_function
+        o = tk.with_ucs4_error_handling(o)
         o = wrap_buggy_function(o)
 
         if evt_type not in self.observers:
@@ -216,8 +219,7 @@ def notify_observers(self, evt_type, evt):
 
         if threading.current_thread() == self.MAIN_THREAD:
             for o in self.observers[evt_type]:
-                # invoke observers with ourselves as first param
-                o(self, evt_type, evt)
+                self.__invoke_observer(o, evt_type, evt)
 
         else:
             # Tkinter is not thread safe. so, observers must be executed on MAIN_THREAD.
@@ -234,12 +236,15 @@ def handle_notifies(self):
                 evt_type, evt = self.notifies.get_nowait()
 
                 for o in self.observers[evt_type]:
-                    # invoke observers with ourselves as first param
-                    o(self, evt_type, evt)
+                    self.__invoke_observer(o, evt_type, evt)
 
         except QueueEmpty:
             pass
 
+    def __invoke_observer(self, observer, event_type, event):
+        # invoke observers with ourselves as first param
+        observer(self, event_type, event)
+
     def mute(self, evt_type):
         self.mutes[evt_type] = True
 
diff --git a/nvpy/view.py b/nvpy/view.py
index 927255a..28c0d19 100644
--- a/nvpy/view.py
+++ b/nvpy/view.py
@@ -11,6 +11,7 @@
 import tkMessageBox
 import utils
 import webbrowser
+import threading
 
 
 class WidgetRedirector:
@@ -940,9 +941,12 @@ def __init__(self, config, notes_list_model):
 
         notes_list_model.add_observer('set:list', self.observer_notes_list)
         self.notes_list_model = notes_list_model
+        self.timer_ids_lock = threading.Lock()
+        self.timer_ids = set()
 
         self.root = None
 
+        tk.Tk.report_callback_exception = self.handle_unexpected_error
         self._create_ui()
         self._bind_events()
 
@@ -958,6 +962,22 @@ def __init__(self, config, notes_list_model):
 
         self.search_entry.focus_set()
 
+    def handle_unexpected_error(self, *args):
+        # An unexpected error has occurred. The program MUST be stop immediately.
+        self.cancel_timers()
+
+        err = args[1]
+        if isinstance(err, tk.Ucs4NotSupportedError):
+            title, msg = 'UCS-4 not supported', str(err)
+        else:
+            import traceback
+            stackTrace = ''.join(traceback.format_exception(*args))
+            title, msg = "Unexpected Error", stackTrace
+
+        logging.error(msg)
+        self.show_error(title, msg)
+        exit(1)
+
     def askyesno(self, title, msg):
         return tkMessageBox.askyesno(title, msg)
 
@@ -1154,7 +1174,7 @@ def _bind_events(self):
 
         self.pinned_checkbutton_var.trace('w', self.handler_pinned_checkbutton)
 
-        self.root.after(self.config.housekeeping_interval_ms, self.handler_housekeeper)
+        self.after(self.config.housekeeping_interval_ms, self.handler_housekeeper)
 
     def _create_menu(self):
         """Utility function to setup main menu.
@@ -1658,7 +1678,7 @@ def handler_housekeeper(self):
             if refresh_notes_list:
                 self.refresh_notes_list()
 
-            self.root.after(self.config.housekeeping_interval_ms, self.handler_housekeeper)
+            self.after(self.config.housekeeping_interval_ms, self.handler_housekeeper)
         except Exception as e:
             self.show_error('Housekeeper error', 'An error occurred during housekeeping.\n' + str(e))
             raise
@@ -1843,9 +1863,9 @@ def is_note_different(self, note):
             return True
 
         tags = note.get('tags', [])
-        
+
         # get list of string tags from ui
-        tag_elements = self.note_existing_tags_frame.children.values() 
+        tag_elements = self.note_existing_tags_frame.children.values()
         ui_tags = [element['text'].replace(' x', '') for element in tag_elements]
 
         if sorted(ui_tags) != sorted(tags):
@@ -2054,4 +2074,21 @@ def word_count(self):
         self.show_info('Word Count', '%d words in total\n%d words in selection' % (tlen, slen))
 
     def after(self, ms, callback):
-        self.root.after(ms, callback)
+        timer_id = 'dummy_value'
+
+        def fn():
+            with self.timer_ids_lock:
+                # timer_id is updated to actual value by self.root.after().
+                self.timer_ids.remove(timer_id)
+
+            callback()
+
+        with self.timer_ids_lock:
+            timer_id = self.root.after(ms, fn)
+            self.timer_ids.add(timer_id)
+            return timer_id
+
+    def cancel_timers(self):
+        with self.timer_ids_lock:
+            for timer_id in self.timer_ids:
+                self.root.after_cancel(timer_id)