Hl2.exe has stopped working.

Recently I installed the Orange Box hl2 pack through steam and I have been unable to get most of the game to work. The HL2 game works fine but that is the only part that I can start. TF2, HL2 Episode 1 and 2 and portal will begin to load through steam then windows comes up with the error: Hl2.exe has stopped working. I have tried: uninstalling the games and then reinstalling them and disabling my firewall. The only thing I have yet to try is reinstalling Steam itself. Any suggestions before I uninstall the whole program?

Edit: I also should mention: I am using vista, I have all the service packs that are available and my drivers are all up to date.