1) Something did not install properly. The fix for this would be to uninstall and re-install the game.

2) You may have a bad play disk. If possible try installing the game on another computer and see if the problem repeats itself.

3) Your CD/DVD drive may be starting to wear out. Watch and see if you get random quirkiness from other disks over time.

That's off the top of my head. I hope that it helps but please understand that I may be off base with these suggestions.