The game is R.O.H.A.N.: Blood Feud.
The game ran fine previous to the Avast! 5 installation. After Avast! 5 was installed, my game client would crash at the first game screen (every time). After uninstalling Avast! 5 and reinstalling Avast! 4 the game ran fine again.
I'm sorry that I can't give you more info than that, but I am 100% positive that Avast! 5 was at fault.
Edit: I guess that I should add that I am running Windows XP Professional 2002, service pack 2, and Firefox browser. My computer is AMD Athlon XP 3000+, 2.16 GHz, 960 MB of RAM.