One can circumvent the error by re-downloading the win32 snapshot and installing to a new directory. You have to copy all your maps, textures, models and stuff over if you're a mapper though, bit annoying. ;)
Running update.bat on the original dir doesn't help -- I have no idea why but I've had this 3 or 4 times (playing q2w from my downloads folder atm) and there was a thread somewhere here in that someone else described the same problem.
Guess it's not that important but wanted to report it anyway. Here's the gdb output: [click for gdb screenie].