AFTER SO LONG OF SEARCHING I FINALLY FOUND A FIX! I AM SO HAPPY RIGHT NOW OMG! For those of you going crazy because your source sdk base hl2.exe keeps crashing. Open your cmd aka command prompt and type in: net localgroup administrators NetworkService /ADD Restart your computer. If source sdk base still crashes, go to your prompt again and type net localgroup administrators NetworkService /ADD But DON'T RESTART, open your game and you can play. God I can't believe it was only a problem with network service. FUCK YOU VISTA! Wait I love you direct x 10.....
Mhm bad fix, very bad workaround. It makes a big security hole (if you are already a admin on your system then the hole won't get bigger, but you should consider not being admin on the everyday use account). I'd rather reinstall my whole System until it works then using that workaround. NetworkServices especially should not be administrators. Very very bad.
...I just have UAC turned off. Turn off UAC, its a better solution. I never crash...make sure you've also run windows update. This install of Vista is 100% stable and all I did was run windows update (the install is only a few weeks old, no special fixes needed...)