Many times, random game glitches are caused by registry errors or invalid hive information. May I suggest running a hard-drive integrity test and have windows repair itself?
You can easily do this by entering into your command prompt:
XP: Start-Run- type
cmd - enter.
Vista/Win 7: Start- in the search bar type
cmd - enter - left-Click on Command Prompt Icon
Once in the command prompt:
Type
chkdsk /F - enter.
You will recieve a message telling you that the disk you need to check is already mounted and asking if it's ok to complete the process on system restart.
Type
Y - enter
Type
exit - enter
Restart your machine and watch the pretty blue screen

(DON'T PRESS ANY KEYS DURING THE PROCESS)
I know it seems like a simple fix, but I've had it work on CS/CS:S many times! Save yourself a bit of headache and give it a shot!
Best of luck! Feel Free to use eGO's Live Tech support if you need anything else!