Sounds like you may still have your old gfx settings if you've changed card for example. I regularly copy my steam cache from machine to machine and have to go through the gfx options on each game to get them running right.
Other than that I'd suggest going to the Valve forums for a specific CS:S problem, you'll find more players there and they've always been very helpful on my CS:S Linux server questions
I had a similar problem with CS 1.6 running on wireless. It has to do with the windows wireless configuration re-establishing its connection periodically. You can shut off the service once you have connected to the wireless network and you'll still be connected.
To shut it off do the following:
Go to control panel > administrative tools > services
Under services, scroll down to find the windows zero configuration then right click on it and select stop.
Whenever you restart your computer you will need to restart the windows zero configuration through the same process.
I figured it out, it was that my Cpu being overclocked was unstable, but thanks anyway guys.
I did get a new card recently and i havent been getting the fps i should be getting. I have a 9800 GT and im getting like 90 fps on Office.