Garry's Mod not starting up

It used to boot up correctly every now and then. And even then, it would take ages to boot, even though my laptop (HP Mini 3100, and jesus christ it’s for gaming, so don’t de-rail my thread).

Now it goes through the “Garry’s mod is starting up” then it goes through the validating menu thing. And after that is complete, it closes and nothing happens after.

Any suggestions?

Meh, I manage to get the game to pop up, then instantly shut down again. No error message.