Thank you for reporting that. I asked for PHP to be upgraded to 5.3, both because its much better than 5.2, and I know the ins and outs of what would change - I just didn't know where things would break. Unfortunately, I have found many VB add-ons (specifically add-ons mind you) to have broken. This is because they haven't updated for PHP 5.3, where as Vbulletin (at least the version we're running) has been.
People interested, or having their own problems, will find this a useful thread:
http://www.vbulletin.org/forum/showthread.php?t=243353. To fix this, comment out the error_reporting() functions in mods, or change them to that of Vbulletin's.
Anyway, fixed.