GMod Starting Error

I have this problem. I just downloaded EasyEngine and now when i try to start GMod, it says this: SteamStartup() failed: SteamStartup(0xf,0x0018E584) failed with error 1:
failed to take master pipe connection lock

Any help?

Restart steam.

It worked! Thanks alot! I already thought i could NEVER play GMod anymore!

Things to do before making a thread like this.

-Restart Steam
If still not working
-Restart Computer
If still not working
-Remove add-on
and if it still fails
-Create Thread.