IM COOL
I'm playing Cod 4 with Java, Steam, AIM, Bluetooth, and GMail notifier open... Same stuff as usual and I'm getting the error.
also Firefox 3 Beta 1
"This error is commonly caused by the steam overlay
In steam goto Settings then the In-Game tab, uncheck the Enable Steam Community In-Game box and press OK.
This seemed to start with the 1.2 Patch which was released yesterday (Nov 22, 2007) on steam."