I am having the same issue. I have a menu in the main frame and one in an iframe on the same page. It appears that when the main menu is loading it is accessing the javascript files in the iframe. Since the <li> elements aren't accessible from within the iframe the 'error menu element not found' alert pops up. I have tried various workarounds but so far nothing seems to work. It looks like a patch may have been provided to fix this issue, is the patch available on the website? I would appreciate any suggestions. Thanks.