Well, I have no idea how to fix it. Even the admin section is affected by it, so I can't remove the offending block from the menu. We'll just have to hope that Blacksway shows up sometime soon so that he can do some of his code magic.
and no it wasn't my fault ... - postnuke seems to like to corrupt its own tables every so often, luckily its just the session info ones, so no data lost.