I have tried to update automatically and have recieved a message saying "The update cannot be installed because we will be unable to copy some files. This is usually due to inconsistent file permissions.: wp-admin/includes/update-core.php". I've checked permissions on that file and they are set correctly at 644. I tried to do a manual install instead, and did everything necessary, but that hasn't launched version 3.8.1 either. Can anyone please suggest anything I am missing to activate the update?