I get this error too (and about 10 small windows appear and then disappear too) if I run the program from the command line, while in the directory where the executable is.  However, if I run the program from a menu shortcut, I don't get the windows.  No idea if the exception is thrown though.

Answers are suggested here: http://mail.python.org/pipermail/python-list/2003-March/192239.html

Here is the output for postr.stable (0.12.3)

~/postr.stable$ ./postr 
/home/gpoo/code/bzr/postr.stable/src/flickrest.py:18: DeprecationWarning: the md5 module is deprecated; use hashlib instead
  import logging, md5, os, mimetools, urllib
Unhandled error in Deferred:
Traceback (most recent call last):

+ Trace 218799

Exception TypeError: "'NoneType' object is not callable" in  ignored


And here is the output for postr.dev (rev 279):
~/code/bzr/postr.dev$ ./postr 
/home/gpoo/code/bzr/postr.dev/src/flickrest.py:18: DeprecationWarning: the md5 module is deprecated; use hashlib instead
  import logging, md5, os, mimetools, urllib
[Failure instance: Traceback (failure with no frames): <class 'twisted.internet.error.ConnectionLost'>: Connection to the other side was lost in a non-clean fashion: Connection lost.
]
Exception TypeError: "'NoneType' object is not callable" in  ignored

This was odd.  The issue was triggered by importing the module bsddb3 inside a function.  Now it is fixed in master.

Here is the fix:

diff --git a/src/util.py b/src/util.py
index bf58995..5974ae1 100644
@@ -17,7 +17,7 @@
 
 import os
 from gi.repository import Gtk, GdkPixbuf
-
+import bsddb3
 
 def greek(size):
     """Take a quantity (like 1873627) and display it in a human-readable rounded
@@ -73,7 +73,6 @@ def get_buddyicon(flickr, data, size=48):
     """Lookup the buddyicon from the data in @data using @flickr and resize it
     to @size pixels."""
     from twisted.web.client import getPage
-    import bsddb3
 
     global __buddy_cache
     if __buddy_cache is None: