88
I had the same problem since I upgraded to XOOPS 2.3, it's becuase I a global variable has been changed to UTF-8. It was originally ISO-8859-1.
You can change it back here:
language/english/global.php
Change
define('_CHARSET', 'UTF-8');
to:
define('_CHARSET', 'ISO-8859-1');
Hope that helps someone.