[SOLVED] Having problem with my horizontal menu

I set up a new site I´m working on on http://kerholsskoli.gagnavist.is

The user then contacted my and said that he had some problems with the dropdown menu, it suddenly disappears although the mouse has not hovered away from it. I have not had this problem on my side mainly because I use Firefox and I have setup on my PC IE9, Google Chrome, Safari for PC and Opera. I can´t recreate this problem in any of those browsers. When I connected to my clients computer I saw he was running IE8 and since this is a school he told me almost every computer in the building had this browser installed.

I have told my client to update his computers but I still need to fix this problem because a lot of people out there use IE8 (although I can´t understand it).

Anybody out there who can check this out for me in IE8 and help me debug this ?