Garry's Mod instant crash to desktop

Hi, so for a couple of days now i’ve had this problem where Garrys mod just crashes when i try to launch it
i dont get a error and i dont see the guy with a physgun
it started with CSS and Gmod freezing my computer with a black screen, now css is working and gmod just crashes
Garrys mod 13 Beta works just fine
running garrys mod with -Width and -Height didnt work
reinstalling gmod didnt work
tried Debugview, forgot that it doesnt work for me anymore
Turned off Antivirus program “Avast” didnt work
Defrag of game Cache in steam didnt work
Verify integrity of game content didnt work
Running in Compatibility mode no success
Both running Steam.exe as Winxp and Run as Admin
and the .exe for gmod as winxp and Run as Admin
Google for hours with no luck
tried with all the -dxlevel and -d3d

Specs:
Windows 7 ultimate 64bit
Intel I5 2500k
Nvidia GT440
mobo: P67A-UD4-B3
RAM: 2x4gb 1800MHZ
computer is about a year old, reinstalled from win7 32bit to win7 64bit 2 months ago, before that gmod worked, but took a break from gmod and hasnt installed it since last friday

Please Help me

-Kazuki

I’ve been having the same problem. No idea what to do now.

-Edit-
System specs just in case:

Intel i7 2600k
12GB RAM
Nvidia GeForce GTX 560 Ti