Gmod launcher Crash

Hey my when i try to start gmod it opens then stays o nthe loadign screen i have defraged run gamebooster and Viewed cache plz help!
System specs
Intel® Core™ i7 CPU 870 @ 2.93 Ghz
Ram: 8.00gb
64-bit
Nvidia 1gb

So you get a garry’s mod window but it freezes?