Gmod not startin (in Background only as Process)

[Miracollix]

Hello,
my G-Mod is starting in Background, that means:
If i start G-Mod it says: "Starting G-Mod..." then i got the loading thin on me Cursor, and after a few seconds, nothing happens,
and if i try to start it again, it says, "G-Mod is already Startet", i have to kill the process in the TaskManager to restart it , but the restart isnt working too.

Thats what i tried:
- deleting addons (worked for about 1 sec and then crashed)
- Startup command (-dxlevel -high)
- restarting PC
- restarting Steam
- reinstalling g-Mod (3x)
- deactivate antivirus
- bought CSS (and downloaded)

nothing worked

any help?

[djjkxbox360]

Have you always had this problem with Gmod? And did you do -dxlevel 80 ? What are your computer specifications?

[Miracollix]

yes since i have bought G-Mod
and my PC is good enought with
32 GB Ram
8x4,5 Ghz Intel