Sounds like you'll need to reinstall the game. Something you could try is running a check disk and set it to automatically fix file system errors and also set it to scan for and attempt recovery of bad sectors. You can find check disk by right clicking on you hard drive and the click properties then go to the tools tab. You might have to reboot you system after you tell it to run the check disk. This could take up to an hour to finsh depending on the size of you hard drive. You could also try a disk Defrag as well.