Hi There,
I think ive found a global bug in the horizontal menu web part. When viewed in firefox 3.5.5 my dropdown is out of line and instead appears at the top left of zoneMenu. I have check some other kentico sites to see if they have the same problem. The one site I found that also uses this webpart has the same problem. Its actually one of Kenticos top sites of 2009. Here are links to my site and the other example site where the problem is showing in firefox 3.5.5 (windows 7 but shouldn't matter). Just hover over the top menu to see the issue.

My site
http://public.bcmcorporate.info/

Site of the year 2009 competition entrant
http://www.kinematicsmfg.com/

If anyone has any idea how to fix this id send you the biggest karma bubble!
Rob