Counter strike Source PROBLEM

Hi.

I have a problem with css. Basicly, i can't even start the game because it freezes right after i start it. And only way to get out of this is to force my pc to reboot. I have no clue what could be the problem.

Specs:
Intel core2 duo 4400
Ati radeon 4850HD
2gb ram

and so on,

and im running x64.

hmm, i got it fixed somehow. had the problem with all games which used hl2.exe. Eventually i changed directx version with command -dxlevel 81 and changed the startup for -window. Then i just switched that options back to normal and it worked perfectly.