Dynamic text not seen in some users' computers

I ve made this website http://www.nicodesign.dk as part of a college assignement.
There is a menu navigation on the bottom of the page (portfolio, events, etc.) built from an external XML file.
The fact is I get complains from some users that they cannot see the menu at all. Is this a screen thing? A flash player issue?
This really drives me crazy!!!:wasted: