I wouldn't doubt a corrupt point system being possible.
I recall Space Quest 4's CD version made it impossible to get 3 points that were possible on the floppy disk version, leaving you unable to ever to get a perfect score. Someone has made an ultimate patch for that game, but I have yet to complete it to see if it works now.
Man, I've been really meaning to complete this game again. I want to use the FM-Towns version since I've never completed that version, but I think Thunderpeel has said a few times that the FM-Towns version doesn't give out the correct score if at all sometimes. That sucks, since I've played my 256 color floppy version to death already (But not carefully enough to max out my score yet).