DDM works fine in IE7 but not in Firefox or IE6

[mindful]

Hi There,
I am setting up UDM4 for the first time and have it working great in IE7. I tested the site with IE6 and Firefox and it does not behave as expected:

• In IE6 the 2nd level DDM expand across the whole page and covers the 1st level DDM.

• In Firefox, the menus don't drop down at all.

Any advice would be great!

Check out the current site at www.omstudio.ca

Alan