I can't launch

Try a support forum?

That happened to me before, on other games.
Never heard of it. What are those games, can you give us some examples? SMB fine for me, exept for the crashes I get everytime when I open it aced I minimized it.

It's most likely a compatibility issue with your GPU. It'd be great if you could post your specs.

Reinstall steam. It worked for me lol

Well worked fine yesterday. I've reinstalled steam, and when to start the game, nada.

i got the same problem with the call of duty war chest, never got around to finding a fix

Maybe try verifying the game cache? Usually when I have a problem with a game, I try that. Usually works.

Generally I'd say it's an issue with your graphics card but if you were playing it fine then I have no idea. Perhaps something posted here will help?