I bought Garrys Mod in a game bundle for a friend yesterday. It came with Counterstrike: Source. The problem is, my friend says that Garrys Mod does not run.

Surely then, they shouldn't sell Garrys Mod alongside Counterstrike: Source if it doesn't work?

Counterstrike: Source is a full Source engine game so there should be no reason why Garrys Mod doesn't work, in theory.

Neither of us are willing to spend any more money for another game just to get Garrys Mod working, when it should work out of the box with another Source game.

Put a support thread in Steam, it might be a bug they never found when Garrys Mod upgraded to Source07...

Or perhaps try logging in with an account with source07 stuff, install garrys mod on that account and then switch..

Hmm... I just checked it out on his laptop and it appears to be working.

/thread