22
Sounds like you need to:
1. re-upload the /class and /include files
2. re-upload all the /themes files
3. In preferences>general settings, and set "check for modified templates" to "yes".
4. in modules admin, refresh/update the system module
5. reset "check for modified templates" to "no".
My guess is that its ./include/cp_functions.php
Hope this works. If it doesn't then the ./include/cp_functions.php file in your download may be corrupt. Another copy of the XOOPS package and upload the file from there.