I'm finishing up a site for my university's EWB chapter, and I've run into a strange issue in explorer.
I'm using a basic unordered list for navigation, but the hover effect does not appear in ie 6. What's strange is that only the first element is affected, and there are no special id or classes associated with it.
The only thing that occured to me is that the order of your CSS seems a bit random. Perhaps there is a cascade issue? Strange that only the initial "About Us" link seems to be affected.