i open up my garry’s mod i bought today, i have orange box and counter strike, when i get to the loading, it just stays there, i waited half an hour than gave up, yes, i un-blocked it but still wont work, help me!!! please 
OMG, i have same problem here.
I find all thing in google but not thing like this error.
I can’t play this game, i using steam to download it.
It stays at Loading mennu
Specs please
You mean my PC ?
Intel® Core™ 2 Dou E6550 @2.33Ghz (2CPUs)
1Gb of Ram
ATI Robility Radeon HD 4300 Series
Memory 512MB
Windows XP
( I still play HL 2 good and no anny lag. )
Your system specs are a bit low for Garry’s Mod
Have you tried restarting your computer and/or Steam?