Interference between ubermenú and upfront elements


I would like to use ubermenú with upfront. Everything is fine except one thing: there is an interference with the "drill-down" ubermenú with the upfront elements (text boxes or images). The problem: it is no possible to clic on a submenú, and that's really a problem.

You can see this problem in this website:

If you click on "Services"/Custom Books or "boxes" you will see that it's no possible.

Could you try to help me to solve this problem?

Thanks in advance,
Marcel Odena