VBulletin Database error

[blanky]

So, I was on my site this morning and everything was fine.. Now about 6 hours later, all the pages on my forum get a database error, and in my email I get this info

MySQL Error : Table './icheater_/vbsession' was created with a different version of MySQL and cannot be read
Error Number : 1033

What does that mean?

Here are a few others..

MySQL Error : MySQL server has gone away
Error Number : 2006

MySQL Error : Lost connection to MySQL server during query
Error Number : 2013

And I didn't touch anything in admin cp, styles, database.. nothing..