Just to confirm: I can reproduce this more or less consistently on all versions of Python 2.2 -> 3.2 on Windows 7. Those are distribution builds -- ie not debug builds I've made myself. But it certainly does occur on a debug build of 2.7.

I'm trying to narrow it down through some instrumentation (read: printf) on the 2.7 branch. The MSDN page for signal warns that a separate thread will be created for the signal handler which will muddy the waters.