I noticed a different issue, the access key was being set to a space, so pressing alt+space in IE caused one of my menus to open, not the Window menu as expected. I use the keyboard to minimize windows, alt+space, n so this was kind of annoying.

if( is_ie && key && parent.base ) {
  tmp = CE( "a", item );
  tmp.href = "#";
+ key = key.replace( /\s+/, "" );
  tmp.accessKey = key;
}