Preparing to launch... Then nothing.

Alright, so I have this problem with all my Valve games and Garry’s Mod. I click the icons on the desktop (or in my Library, makes no difference) and the Preparing to launch (Game)… window comes up, as always. But after it’s done, it just disappears, and whatever game comes up for a second in a transparent window. It’s not the first time I’ve played ANY of these games, I’ve played them frequently as possible. My computer was cluttered so I decided to reformat and reinstall windows and I updated the computer and updated DX9. Also, for some reason, my speakers aren’t working either. Not sure if that has any significance. Any ideas?

I’ve tried a clean install of GMod, adding all sorts of prefixes to my launch settings, but nothing from Facepunch, Steam Support, or Google has helped me along yet.

i have the same issue,but seems to be more to that i tried going to the file and launching it manually from Stream/steamapps/(username)/then garrysmod i clicked on the hl2 Application then i get a error saying this: “Setup file ‘gameinfo.txt’ doesn’t exist in subdirectory ‘hl2’. Check your -game parameter or VCONFIG setting.” if anyone got any advice on how to solve this issue please tell us.xD i got no idea what it’s talking about.

windows vista
Processor:Intel®Core™Duo CPU T6400 @ 2.00 GHz