Just bought GMod and it wont start

I just bought Gmod of steam, and i have HL2/portal/TF2 installed, and when i start it up, it freezes, no explanation or what not, i just want to know if anyone else has been having this problem

i had this problem too, just wait like 20 min and go back to ur computer and if its not done just try restarting ur computer then do it again.

Post your specs.

works, shoulda read the stickys up top about restarting steam, lol