Gmod stuck on Preparing to launch

my friend who plays gmod quite a bit has started to rage at it recently. Since a new install of windows 7, his Gmod takes ages to launch, except when its freshly installed, and even then it runs once fine and not again, he keeps claiming its steams fault and how garry is such a fag blah blah blah you know the rants… he has verified his cache, defragged, and it is a 100% legal copy from steam, non of his other games come up with this problem, so what could be wrong?

It’s windows 7. O_O