Off and on for the last couple weeks I've encountered an error running "test.exe" when visiting the Everquest Allakhazam website. Today I happened to go on from my computer at work and received a warning from Symantec Endpoint Protection that test.exe was identified as Trojan.Bamital, a trojan that hijacks searches and injects ads into them.
My guess would be that one of your advertisers has this trojan embedded in their ads. I know that hackers have been found to be using similar tactics to get websites like the Washington Post, New York Times and Monsster.com to serve trojans, so I'm not surprised that they've targeted you as well.
Threat Details on Symantec's website