Up keyboard shortcut doesn't work anymore

Binary package hint: xine-ui

OK, this is a weird one. [Up] is assigned to "increment playback speed" in the keymap editor of xine (xine-ui 0.99.5+cvs20070914-2.1 in karmic), but pressing the up key doesn't increase the playback speed. Pressing Down decreases playback speed (which is what it's assigned to). If I assign e.g. [y] to "increment playback speed" then it works with the Y key, but if I reassign it to [Up] then it doesn't work with the Up key. It's obvious the Up key works, since xine's keymap editor recognizes it when I press Grab, and the Up key works in all other apps, too. And the Up key isn't assigned to anything else also (at least not according to xine's keymap editor, which complains if I try to assign the Up key to more than one action).