Frog, I have the exact same problems with speed and pause toggles using minimal UI, and have tried reassigning various keys from the defaults, to no avail. As it is, I can change speeds with keys assigned to a single speed (not as a toggle), but cannot pause easily, and still hear the continuous "thunk-thunk-thunk-thunk" when I use the speed-changing keys. I'm on a GF4, however, so I don't think it's just a specific graphics card problem..