The file_manager block (aka MyFiles) is not working with 1.8. It uses several old calls to user_teachers and user_students table. David Tong has supplied some changes to the lib.php print_lib.php and sharing.php files (see attached diff) which I am going to apply to the 18STABLE branch. David also notes that there are places where user.idnumber rather than user.id are used and these will need to be cleaned up. The code in general is very much in need of some attention. Related to discussion at: http://moodle.org/mod/forum/discuss.php?d=91089