So I tried downloading Tiberian Sun from FilePlanet. It worked great until trying to start the game. When I start I get this message:

"One or more DLL files is missing or damaged. Please reinstall."

So I did, I re-downloaded and reinstalled it. Got the same message.
So then I go out and buy The First Decade. The other games work great, but when I try to play Tiberian Sun, I get the message again.

"One or more DLL files is missing or damaged. Please reinstall."

Has anyone else had this issue? Is there any way to find out what I'm doing wrong and how to fix it?