Thank you 13ti, that worked for me!
Same problem here, and it’s not solved by adding <p></p>-tags.
I have similar problems after moving my blog to a different server.
The blog works just fine for visitors, but when I’m trying to login as Admin, I get “You do not have sufficient permissions to access this page”.
Updating the database or modifying .htaccess or deleting plugins doesn’t help.
