Originally Posted by webmaster

Actually, it has nothing to do with vBulletin or PHP. There are two main ad sections on the site, the top leaderboard and left wide tower. Whoever setup the ad campaign that is causing a problem put a leaderboard (728x90) creative in a space that is only intended to display a wide tower (160x600) ad. If someone can tell me which advertisement is the culprit, I can either pass it along to IB or see if I can fix it.

Update: it should be fixed now.