Users of Grisoft AVG, upon updating AVG today are being told they're infected with "Trojan horse Generic5.JMY" in the ...World of Warcraft\fmod.dll when they load WoW.
This is a false positive that should be fixed by an update later today.
"At this point, the only solution found to work is to disable AVG's resident shield, but this will leave you unprotected when connected to Warcraft" (though, the bottom of the article lists a possible work-around for Vista users).
http://chaseandsam.com/2007/07/worl