Hmmm, you're the second person to experience this...
I think that the problem is due to a trick I tried to implement based on one of Max's suggestions. In order to move the text on the home page higher in the code, I've got the navigation buttons in a second row.
The problem is that I can't recreate the situation you experienced. When I review my site with IE4, NN4, NN3, and AOL3 everything looks perfect (the navigation is a smidge lower than on subsequent pages, but not noticably.)
Thanks, it looks like I've got to do some more fine-tuning.