For pinball, there was a bug with the collision detector in the 64 bit version they could not fix.

"Two of us tried to debug the program to figure out what was going on, but given that this was code written several years earlier by an outside company, and that nobody at Microsoft ever understood how the code worked (much less still understood it), and that most of the code was completely uncommented, we simply couldn’t figure out why the collision detector was not working. Heck, we couldn’t even find the collision detector!"

Source: https://blogs.msdn.microsoft.com/oldnewthing/20121218-00/?p=...