Can't see profile

I can't look at my own profile or lists or anything useful. A white screen with the following text pops up. Its been doing it for a number of hours now. :-(

"A critical error has occured.

This error has been logged and will be dealt with asap."

A little help please?

I've fixed it. It's to do with a problem with customlists but I don't know what is causing it yet. Any information on what you were doing with custom lists before the profile failed would be useful.