From your PHPMyAdmin do the following
from the left menu go to '#_extentions' (# = your table prefix)
Look for 'mod_logged' . make sure that the 'enabled' field is set to '1' in that record. Then go to the administrator area and look for a module that relates to the user that is currently logged in.
If you find this module in the administrator area go to PHPMyAdmin and click on the 'SQL' button, and change the '#' to your database table prefix.
UPDATE `#_extensions` SET `enabled` = '1';