offlineimap crashes repeatedly

[Stefan Thull <mail@xxxxxxxxxxxxxxx>]

Hello
I'm using offlineimap 4.0.8 on Suse 9.2 with python 2.3.4
After installation, when I try to sync with my imap-account it syncs for 
a while and then crashes with lot's of error-messages. When I try to 
restart offlineimap it syncs again but crashes again. (The point where 
it stops are always different; sometimes I manage to sync the whole 
account.)
I send you some of the error messages.
What could be the problem?
Thanks in advance
Stefan Thull
---------
stth@linuxdad:~> offlineimap
Thread 'Folder sync df-imap[INBOX]' terminated with exception:
Traceback (most recent call last):
  File "/usr/lib/python2.3/site-packages/offlineimap/threadutil.py", 
line 153, in run
    Thread.run(self)
  File "/usr/lib/python2.3/threading.py", line 416, in run
    self.__target(*self.__args, **self.__kwargs)
  File "/usr/lib/python2.3/site-packages/offlineimap/accounts.py", line 
204, in syncfolder
    ui.loadmessagelist(remoterepos, remotefolder)
  File 
"/usr/lib/python2.3/site-packages/offlineimap/ui/Blinkenlights.py", line 
47, in loadmessagelist
    s._msg("Scanning folder [%s/%s]" % (s.getnicename(repos),
  File "/usr/lib/python2.3/site-packages/offlineimap/ui/UIBase.py", line 
49, in _msg
    s._display(msg)
  File "/usr/lib/python2.3/site-packages/offlineimap/ui/Tk.py", line 
527, in _display
    while float(s.text.index(END)) > s.bufferlines + 2.0:
ValueError: empty string for float()


No debug messages were logged for Folder sync df-imap[INBOX].
Unhandled exception in thread started by <bound method 
InstanceLimitedThread.__bootstrap of <InstanceLimitedThread(Folder sync 
df-imap[INBOX.Admin], stopped daemon)>>
Traceback (most recent call last):
  File "/usr/lib/python2.3/threading.py", line 451, in __bootstrap
    self.__stop()
  File "/usr/lib/python2.3/threading.py", line 460, in __stop
    self.__block.notifyAll()
  File "/usr/lib/python2.3/threading.py", line 256, in notifyAll
    self.notify(len(self.__waiters))
  File "/usr/lib/python2.3/threading.py", line 238, in notify
    currentThread() # for side-effect
TypeError: 'NoneType' object is not callable

-------Or Errors like: -----------
stth@linuxdad:~> offlineimap
Thread 'Folder sync df-imap[INBOX.IN-BGriech]' terminated with exception:
Traceback (most recent call last):
  File "/usr/lib/python2.3/site-packages/offlineimap/threadutil.py", 
line 153, in run
    Thread.run(self)
  File "/usr/lib/python2.3/threading.py", line 416, in run
    self.__target(*self.__args, **self.__kwargs)
  File "/usr/lib/python2.3/site-packages/offlineimap/accounts.py", line 
170, in syncfolder
    ui.loadmessagelist(localrepos, localfolder)
  File 
"/usr/lib/python2.3/site-packages/offlineimap/ui/Blinkenlights.py", line 
47, in loadmessagelist
    s._msg("Scanning folder [%s/%s]" % (s.getnicename(repos),
  File "/usr/lib/python2.3/site-packages/offlineimap/ui/UIBase.py", line 
49, in _msg
    s._display(msg)
  File "/usr/lib/python2.3/site-packages/offlineimap/ui/Tk.py", line 
527, in _display
    while float(s.text.index(END)) > s.bufferlines + 2.0:
ValueError: invalid literal for float(): None