Have a look into this small issue!

[maar3amt]

Hi ppl after server change we got a bug like, members become a guests in postbit, in profile everything is fine just problem in postbit.

Any ideas?

http://img38.imageshack.us/img38/4214/ss20091128035255.png

[Lynne]

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

Then browse the site using that totally default vbulletin style - do you still have the same problem?

If it is still happening - Try disabling your modifications/plugins and see if you still have this problem.
Note: To temporarily disable the plugin system, edit config.php and add this line right under <?php

define('DISABLE_HOOKS', true);