I also had something like this happen at one point. It's most definitely a sign of lack of memory available to run the game. :? Sometimes, a good ol' fashioned reboot of the computer can help refresh your virtual memory and RAM, but if that doesn't help you might want to consider researching compatible video cards just in case yours is on it's way out.
Have you tried everything that MissDoh suggested in your previous thread? If not, it might help you out a bit.
Also, if you haven't already, check out the tutorial on
Sim Wardrobe for computer optimization tips (mainly with XP, but I'm sure there's a way to translate some of those things to Vista if possible). :angel: