I have set up a website using the yui menus. Generally speaking this is going well and there are relatively few problems across browsers and operating systems. However as luck would have it, the menus are not working on the clients machine which uses IE7. Specifically links with class .yuimenubarnav do not work although you can see the url flashing up in the browser status bar. However submenu links and one image that happens to be an image rather than text but is in the menu bar does work.
However I played around a little more and I found that if I stuck a div between the "li" and the "a" the problem went away. The formatting is upset but this seems to be a viable work around in principle.
The IE version is 7.06000.1685
The machine is an HP G7000 Notebook PC
The OS is Vista 6.0 SP0.