This works for the PowerPC Python compiled with gcc 3.3
on OS X using fink.  I suspect it's broader based than
that, but I don't have the ability to check properly.

Here's how to make it segment fault:

x = (basestring,)
for i in xrange(0, 1000000):
   x = (x,)
issubclass(str, x)

At least, it segment faults at the interactive prompt
this way.  I don't know if it does when it's executed
from a file.