[Felix The Assassin]

This it where it gets tricky. You can see the files, due to they are installed on the puter. The reason you cannot play them goes back to the restore point. If the restore point was before the games were insatlled, they are not in the 'registry'. Since you can't play them, I'm sure that is the problem. Attempt to access the save game folders, and copy whatever save games you want to a seperate location. You will have to manually un-install all the files, you won't be able to through remove programs, as they are not in the registry. Remove all of them, then re-install, move your save games into the save game folder and repeat until all is well.

Others might suggest just to re-install, the problem with this can lead to a double of the filing system. Instead of only needing x amount, it could double and use x,y, and z amount on the hdd. This could also lead to a 'ghosting' in the file system. Which in turn will create game crashes, and you will be stymied as to why.