[kh99]

Oh, right...what Lynne always says (how could I forget)...

Do you use custom styles? If so, try

Create a new style with no parent:
?Styles & Templates > Style Manager > Add New Style
?Parent Style: No Parent Style
?Title: Default vBulletin
?Allow User Selection: Yes
?Save

and see if you still have the problem. Also, try disabling plugins

Note: To temporarily disable the plugin system, edit includes/config.php and add this line right under <?php

PHP Code:

define('DISABLE_HOOKS', true);