It really is because there is no user upload max in moodle. What version of moodle, php, mysql and server you have?
The reason could be somewhere else than upload max values. That 10 bytes comes from some wrong place (corrupted file, database error...)
Check first that your config.php has no signs after last ?>
(people allways suggest this if there is no reasonable explanation...)
Next you could debug possible errors (from server or moodle settings)