Ok, this might be a weird one.
I can't seem to use the 'Badges' and 'My Account' menus that appear in the top-right after you login. When I mouse over the headings, I see a menu appear, but if I move the mouse pointer down, it leaves the menu heading's focus, and the menu disappears. This was happening with SeaMonkey 1.1.9 on Win2k, WinXP, and interestingly enough, Fedora Linux. Just as curious, when using the exact same browser on MacOS X 10.4 (Tiger), the menus work as expected.
And just to be sure my atypical choice of browsers was less of a contributing factor, I downloaded a clean Firefox 3.0.1 and got the same behaviour.
The one workaround I came up with is to click on the menu heading and drag the mouse pointer down. Then the menu stays up and I can select items from it.