Thanks!
As I don't have a Mac, a friend tested these for me in Firefox-Mac.
http://ruhaniat.org/DeMo4TeSt/nocust.htm (with the 'stock' version of udm-custom..js -- "loads without hanging and presents a statically positioned menu in upper left corner, and for the choices with subchoices, the subchoices slide out to the right."
http://ruhaniat.org/DeMo4TeSt/noslide.htm (with link to sliding menus script commented out but using my edited version of udm-custom) ... "presents the page, with a blank box where the menu ought to be, and the mouse changes from arrow to linking finger in some places in it -- probably the areas where the subchoice menus are, but the browser hangs and needs to be shut down to clear it."
Thanks so much for looking at this, and I hope it's easy to fix!
-- HB