Hi Sidroe,
This sounds suspiciously like a memory error to me --- a programming memory error. It could have been there for a long time, then suddenly was exposed by the Windows update. What I mean my "programming memory error" is that there may be an attempt to read/write too large a value for the memory allocated, a null pointer, perhaps use of an uninitialized value, and that type of thing. These are very difficult to locate manually, much easier to isolate with memory checking tools by the progammer (i.e. by Guido). I myself program all my math routines and technical stuff in Linux, then check for memory errors with valgrind. When they pass the memory checks, I copy the routines into Windows folders, then use Visual Studio. Doing this for every routine has saved me countless hours of fruitless troubleshooting. I don't know what would be comparable for Windows, but you might ask Guido if he's tested for memory errors such as I have described. Unless he has the specific version of Windows installed that you do on a similar machine, he may never find this problem, nor may anyone else, without a memory checking tool.
Good luck with this problem!
Regards,
Dave Clark