The protection sstem won't let me play anymore

[The_Blockade_Runner]

All of a sudden, one day I go to load up my game and the protection system says error, check disk. Ive checked the disc and it is still as clean as a baby's butt. The key code is still entered correctly, and the protection system still won't let me play.

It says something like error, check disc is a legit copy and/or code key is entered corectly. Ive tried uninstalling and reistalling but that didn't work either.

What else can I do? This is my favorite game but now I can't play it.