That error message is an indication of database corruption. A post to the forum
before you stayed up all night would have saved you a lot of frustration, because once we realized you were using MySQL, we would have suggested that you repair the tables.
Do you use any remote clients to post to your blog? There aren't too many things internal to MT (actually, I don't know of
any things offhand) that will corrupt your database like that. MySQL is usually pretty stable, which is why it was added as an option over Berkeley.
As I stated the other day in another thread - I've used MT for nearly two years now, and it's been a smooth ride the entire time - that's with both Berkeley and MySQL databases. I can't imagine I've just been extremely lucky (because if I were that lucky, I'd be a lotto winner by now).
If you're running into lots of "bugs", you might want to spend more time on the forum finding out if they really
are bugs before you lose any more sleep.