Corrupt User?

So here is a new one. I seem to have a corrupt user. I can't go to their profile and stranger yet, when I go to the user in the dashboard I can't search for them AND I can't even pull up the page for them. I can go to every other page in the dashboard for users, but the page that contains that user just hangs. Any thoughts? Do I need to get into the database of users and somehow reset them? I tried to logon as them, as I know that password and it just hangs. Blank screen - same as when I try to access other ways.

Thanks, David