I have this error also accross the banner in my admin page and cannot access admin section. I was told by 1&1 my site was hacked about 2 weeks ago, I have not added any modules or touched site in some time so I didn't cause issue.
I would like to know how to get rid of this problem though? Someone mentioned there was a patch to install. If I cannot access back end, how do I edit anything? I can edit mage.php file, but I am not a programmer so can someone please advise what I need to do?