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Check your XOOPS database in phpmyadmin and see if there are any errors listed for your tables. It sounds to me like you could have either a database problem, or you don't have all the files for your modules uploaded correctly. Look at your files on your server and compare them with original files and check your database. If you find nothing wrong after doing this, we can look at other solutions to your problems.
You may have to try re-installing XOOPS if all else fails.