Okay... I can confirm a temporary solution (because I don't want to go through all 20+ pages of my site doing this) that you can just set individual nav bars set as the rollover images with links and it works.
I didn't try with a larger image rollover, but with my menu page here:
Portfolio - I fixed the "about" button by moving those two images to the 'navbar' folder in my C:\BlueVoda and deleted the default text, set the link address and published it.
(the other nav buttons on that page still don't work because I didn't fix them yet).
Great find angus!! :) Now I can at least get this one page working until whatever bug gets fixed in BV10.