Internet Explorer 8, windows 7 (I haven't tested other browsers).
Issue #1: If you edit a page, and type nothing, but move around in the page with arrows, ctrl+end etc, the editor thinks something changed, and gives you the "are you sure you want to navigate away" warning when you click Cancel.
Issue #2: If the first character you type when editing is a control sequence (I start with ctrl+end a lot to add to the end of a page), the "control" part is eaten by the key handler, so the page can be marked changed. The next time you use the sequence, it works. I find this very annoying, but it's obviously not the most severe bug in the world.