5
also the debugger works by line number of the page you view when u get the error..
so if u want to try and trace it, view the source of the page you are on and save it as a txt file.. then open it up in your web editor and find that exact line (770) and it should give you some indication of where it's saying there's a problem.. it could be an ad, a theme error, or anything that's actually shown on the page at the time..