Bug in Python 2.1.1?

[Xiao-Qin Xia]

Hi,

I write a program for simulation in pure python with Tkinter. In order to be
able to interrupt at any time, the simulation module runs as a thread. It
can run days in python 2.0, but if running python 2.1.1 it will be closed by
windows 2000 in about half a hour. If running not as a thread,  no problem.
Does that mean Python 2.1.1 has a bug in thread management?

Cheers,
Xiao-Qin