domain mapping is breaking my site's layout

Hi,

I have a multisite that needs to mapped domains because I will offer blogs for our users.. but when I am activating the domain mapping plugin, it is breaking the layout of the site. I tried deactivating all plugins, activating them one by one, changing themes, etc. and problem is still there.

this is the site when domain mapping is not activated, the nav should be in a tabbed format:

http://i.imgur.com/ym7PxTa.jpg

and this is the site when domain mapping is activated, all elements are on one page:

http://i.imgur.com/BuOreqs.jpg

thanks