need help with bizarre error caught in debugger. execution is hanging

[omission9]

Any advice on the following would be much appreciated. I have thrown 
everything I have at it and am completely stumped. I apologize for the 
length, I have tried to be as succint as possible.

I have a pythoncard/wxPython application. The application works well 
except that users were reporting occasional crashes. The application 
would simply stop and just hang. I was able to reproduce the bug 
faithfully and ran the application in the python debugger pdb.py.
The trace is below and I simply cannot understand why it is hanging 
where it is. The application gets stuck executing

return len(self.data[0])

This works many many times during the applications execution, indeed 
several successful runs of this line are visible immediatley above the 
hang. I have also printed out the value of self.data. This is a list 
containing 12 inner lists each of length 3 at the point of the hang and 
is never larger than that.
What on earth could cause this to stop the interpreter cold in its 
tracks without an exception being thrown? CPU usage on the machine is 
high throughout the application's execution and stays as such after the 
"hang" begins. I eventually kill the app although I have let it run for 
a long time and it never leaves this line.
For what its worth, I am using python 2.3 on windows2k.

Anyone have idea what could be happening?

  c:\python23\lib\site-packages\wxpython\grid.py(664)_setOORInfo()->None
  -> return val
  (Pdb) s
  --Return--
   c:\python23\lib\site-packages\wxpython\grid.py(850)__init__()->None
  -> self._setOORInfo(self)
  (Pdb) s

 
c:\cygwin\home\ar881\development\bt_analysis\console\ndbbtable.py(17)__init

  __()
  -> self.data = data
  (Pdb) s

 
c:\cygwin\home\ar881\development\bt_analysis\console\ndbbtable.py(18)__init

  __()
  -> self.colLabels = headings
  (Pdb) s
  --Return--
c:\cygwin\home\ar881\development\bt_analysis\console\ndbbtable.py(18)__init

  __()->None
  -> self.colLabels = headings
  (Pdb) s

 
c:\cygwin\home\ar881\development\bt_analysis\console\ndbbtablegrid.py(15)__

  init__()
  -> self.colsizes = colsizes
  (Pdb) s

 
c:\cygwin\home\ar881\development\bt_analysis\console\ndbbtablegrid.py(16)__

  init__()
  -> self.SetTable(table, True)
  (Pdb) s
  --Call--
  c:\python23\lib\site-packages\wxpython\grid.py(993)SetTable()
  -> def SetTable(self, *_args, **_kwargs):
  (Pdb) s
  > c:\python23\lib\site-packages\wxpython\grid.py(994)SetTable()
  -> val = gridc.wxGrid_SetTable(self, *_args, **_kwargs)
  (Pdb) s
  --Call--
c:\cygwin\home\ar881\development\bt_analysis\console\ndbbtable.py(27)GetNumberRows()
  -> def GetNumberRows(self):
  (Pdb) s
c:\cygwin\home\ar881\development\bt_analysis\console\ndbbtable.py(28)GetNumberRows()
  -> return len(self.data)
  (Pdb) s
  --Return--
c:\cygwin\home\ar881\development\bt_analysis\console\ndbbtable.py(28)GetNumberRows()->12
  -> return len(self.data)
  (Pdb) s
  --Call--
c:\cygwin\home\ar881\development\bt_analysis\console\ndbbtable.py(30)GetNumberCols()
  -> def GetNumberCols(self):
  (Pdb) s
c:\cygwin\home\ar881\development\bt_analysis\console\ndbbtable.py(31)GetNumberCols()
  -> if len(self.data) <= 0:
  (Pdb) s
c:\cygwin\home\ar881\development\bt_analysis\console\ndbbtable.py(34)GetNumberCols()
  -> return len(self.data[0])
  (Pdb) s
--Return--

 
c:\cygwin\home\ar881\development\bt_analysis\console\ndbbtable.py(34)GetNumberCols()->3
  -> return len(self.data[0])
  (Pdb) s