Garry's Mod and Counter Strike: Source are not loading

[Maximus]

When I load, This message pops up:

"SteamStartup() failed: SteamStartup(0xf,0x0012E584) failed with error 1: failed to take master pipe connection lock"

Ever since I downloaded Gmod.

1. Before this happened I could run CSS, so it isn't a video card problem.
2. I have enough RAM
3. I have enough Memory