One more time, restart computer/kill hl2 process each time you try to run it again, because even if it's not running it's still in your active processes list(alt+ctrl+del > start task manager > processes > KILL HL2.exe). Download fresh css from css.setti.info, patch it(patch is available there for download too), run it in xp mode as administrator, and make sure to erase everything you have now if you install the new css in the same directory. Make sure to have STEAM off. Let us know what's up after you go through these steps.