
The next step i would do:
1. Try to repair the databse tables in ex. phpmyadmin
2. Deactivate one module one thing at a time, ex. rename per ftp
Maybe you can check is the problem inside the database.
In some cases modules they are not up-to-date (i mean old versions for old xoops versions) bring or come to clash. Did you try or did you has a chance to install a clean new xoops system to see if xoops, the server or anything else the problem?
Greets