I was the one who discovered the problem, using Python 2.2.2. Curiously, "someone" missed it because he was using vc6 instead of vc7.
So you were using VC7. If so, using it for what? Every stick of code in question, or were you mixing VC7-compiled code with VC6-compiled code? If the latter, talk to Microsoft (by most accounts their runtime support libraries aren't compatible with each other).
[traceback freeing a tuple]
Both answers seem to amount to "'someone' must have a bug in his code". Am I reading that correctly?
Yes, for the right meaning of "someone". Possibilities beyond you include Python and Microsoft. Best guess I can make based on what you haven't told us yet is that you were mixing the released Python 2.2.2 Windows core DLL (built with MSVC6) with extension code using MSVC7 C runtime libraries. Right or wrong?