Gmod crash at startup... No errors

Hey everyone,
My gmod crash whenever i try to launch… remains fixed with the loading cursor and nothing happen
i have all the time open the task manager and close the process…

can help me?

but i seen gmod start when i put this in the launch command: -dxlevel80


Edit: Now my garrysmod works! But in the advanced video options my hardware directx level is 8.0… and the software dx level is 9.0…
but before i had hardware/software 9.0 …

whats the problem?