5
Can you turn on debug mode? If not from the interface, can you turn it on from the database?
Post any error messages.
This message says a certain file can't be read. Check the file permissions on it? Try replacing that file with the original file from the XOOPS version you are using.
Finally, has anything changed recently? Did you do an update, install anything? Did your ISP?
I'll note that I'm not a 2.2.x user, but the branches aren't that far off either.
Good luck!