Thanks for the help. But it appears I've ran into some kind of other bug. ddbg:
Unhandled Exception: EXCEPTION_ACCESS_VIOLATION(0xc0000005) at __aaInX (0x0041b616) thread(552) That seems like the hash method for checking keys. I have a static int[int] hash which I'm not sharing with other threads, I just check if a key is in there. Damn, this will take some work to make a good test case..