CSS dropdown not working fine in IE6

This is really puzzling behavior. The drop down works fine in Firefox and IE7. It even works on the first page of the site in IE6.

See https://www.metayage.com. The drop down for services and team works perfectly.

However in any of the subpage of services it stops working.
For example https://metayage.com/our-services/ip-audit/

The code is exactly the same in both place. I can’t seem to figure out why this is happening.