Exploit Lucky Exploit Pack

When playing Left 4 Dead for awhile like 20 minutes, AVG will pop up a message saying:

Accessed file is infected
-----------------------------

Theat detected.

File name: Exploit Lucky Exploit Pack

Process name:C/Program Files/Steam/Steamapps/Common/left 4 dead/left4dead.exe

Process ID: 5004

I gathered some info on it from:

http://answers.yahoo.com/question/in…3231138AApIkWH

http://www.finjan.com/MCRCblog.aspx?EntryId=2213

It seems the threat will be automatically blocked by AVG. But the info also said the message happened when using browser or other applications. That sound like something is doing something to my left4dead.exe or it's infected and need to be cleaned. Plus i don't want the pop-up messages every time when playing for about 20 minutes as it will automatically minimized the game and bring me to the desktop. Any idea?