It might be a day or two before I get to test CS:S on the wife's machine. It's installed, but the key is tied to my account.
Brain fart... sorry... got a trouble ticket open in the hope of switching the key to her.
I read through all the CS threads here... and a bunch elsewhere. The best I can figure is that CS is hit or miss. Nobody seems to have nailed down why some guys suffer ping spikes while others don't?
In the meantime, are you guys running anti virus apps? What kind and what level of protection are you running? Do you have real-time protection enabled, and if so what does it scan? Does your AV have a game mode? What, if any firewalls do you use? Have you tried running as admin in XP compatibility mode?