I came to this thread while searching for an answer to, "How to rebuild bitfields in vbulletin"
For anyone else seeking the same solution, here you go. Copy the link below and change 'yoursite.com' to your own URL.
http://www.yoursite.com/admincp/inde...buildbitfields
If you are rebuilding because a previous mod or plugin is causing issues (even if you already uninstalled it), then be sure to go in to /includes/xml and delete any xml files that are related to that mod. Do that before you rebuild bit fields.