Can we get a link to see what is going on? Also, are those all totally default templates? And, do you have totally default css?
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 that page using that totally default vbulletin style - do you still have the same problem?