Are you serious...
Originally Posted by Steam Support
Certain Anti-Virus applications such as AVG 7.5, Nod32 and Norton have been confirmed to cause instability with Steam and Source Engine games. This software must be fully uninstalled from your system until the Anti-Virus software developers can resolve these issues. If you are not comfortable with using alternative Anti-Virus protection, then we recommend contacting your Anti-Virus developer for more information.
Yet in another article, they say if you're experiencing crashes, you should scan your computer for viruses with an application such as NOD32.
I've been having a ton of problems with crashing in Team Fortress 2, and I'm trying to get to the bottom of it. I'll see if disabling NOD helps, but it would be ridiculous if I had to uninstall it.
Oh, and I also run Spy Sweeper, which they want me to fully uninstall...