I believe it was actually an ambient check of things like floating point arithmetic that ran on an ongoing basis, and if it ever failed we popped up an error me

I believe it was actually an ambient check of things like floating point arithmetic that ran on an ongoing basis, and if it ever failed we popped up an error message. We already shipped with debug assertions enabled in release builds, so it wouldn't have been unprecedented to do things like validate result bytes after doing big memcpy operations or things like that. Not sure if we did, though.