7
Hi,
if you can login and work with admin can you enable phpdebug (try both modes) and look for errors in the main page. If you have access to server error logs you may look for errors there. Maybe your hosting provider can help with that...
What is the XOOPS version?
What modules do you have installed?
Do you have module for startup?
What blocks do you have for startup page?
Any hacks?
You may try to disable blocks on top page (except for main menu, user menu, login) and see if this makes a change. If you have a module for startup disable that too.
Also you may try to clear cache and templates cache...