Could have been a hacker... Tom runs a huge site and i doubt he would intentionally do something like spread a virus to ruin his reputation. You guys could also have an infected hosts file, and the pichunter.com you see isn't the real pichunter. I run alot of protection and i've never noticed any warnings when accessing pichunter, I usually am just in the submit area though.
Be sure to do a scan with adaware and spybot, and use spybot to immunize your system. And use firefox ;)