Garry's Mod crashs on startup

If I start Garry’s Mod.
It crashs instantly after displaying the blue start up window with the message “hl2.exe has stopped working!”.
I reinstallied it already. Reinstalled Steam. Cleared Registry of GMod. Removed the garrysmod folder.

Didnt work.

Can somebody help me?

Try validating TF2

Damn, son.
You saved me. Thanks.