It might be IE. ultimately the WP menus screen is included with WordPress itself and is core code. Theme like Genesis can use it, but the only way it could be fixed is a patch to WP itself.
These forums were CLOSED to new posts on November 19th, 2012. New forums are here: http://www.studiopress.com/forums/
and you will need to SIGN UP AGAIN.
If you need assitance with setting up your theme, go to http://my.studiopress.com/
and read the SETUP links or the TUTORIALS link on the side tab.
If you need Account Assistance
, file a help desk ticket at the same location.