Okay - this has been fixed.
Apparently, if you have Norton Internet Security enabled on your computer you were seeing this giant crazy Google ad on the top of the page. The reason was that Norton *thinks* it's blocking an ad up there, but it was really only blocking the part of the code that makes the ad the correct size (a slim little banner - not very annoying at all). Thus Norton actually made the ad bigger instead of blocking it. What a scam!
I haven't ever had an opinion on ad blocking before, but now I'm mad. I work hard on this site and Norton comes along and actually changes the code before passing it to your browser, completely messing up my nice mult-browser format. Argg.
Anyway, if things ever seem completely out of place for more than a couple hours, please let me know. I might not even see the problem (as I didn't here until I picked up someone else's computer).