Same problem here in fresh install of 1.5.1 No mods or edits its stock u Get the following message: PHP Warning: constant(): Couldn't find constant in /..includes/functions/admin_access.php on line 38, referer: http://.../categories.php?cPath=11&c...=edit_category

An 8mb error log file has been growing and growing because of this error. Is there a fix? I tried the above and i get an "Error please refresh this page" when trying to edit categories.

The problem also does not occur on superuser profile. Only occurs on custom profiles.