Help! Site suddenly dead, throwing new error. Need fix!

I'm suddenly getting the following error:

Fatal error: Cannot redeclare tla_ads() (previously declared in /home/.sites/13/site245/web/includes/common.inc(1158) : eval()'d code:7) in /home/.sites/13/site245/web/includes/common.inc(1158) : eval()'d code on line 45

And I can't login to my web site, or at the moment, even raise the front page *to* login. as admin or anyone else (http://www.whatdoesthatmean.com)

The last thing I did to it, a few days ago, was add a new block with the Google AdSense for Search code. Everything seemed to be working fine then, and I while I didn't access the site itself for a couple of days, i did check my adsense reports and new searches seemed to being generated over that time, so I presume the site is working.

How can I fix this?