One thing that stands out about the Lithe skin is that it uses a large (9MB) bitmap for the position knob/slider, but if that is the cause of the problem it shouldn't happen when XMPlay is minimized, as the position knob/slider shouldn't be updated then. Are you sure the problem did occur even when XMPlay was minimized, eg. might it have been in the tray without being minimized?
I am not sure at all because I don't minimize first but just click on the tray button to hide and show. The position knob/slider I never see because it runs in mini-mode all the time. The only things that move in mini-mode panel is the round position indicator on the left, the song title and track time. I will test Lithe again so we can draw some conclusions on the sucker. Right now, I have it set the way it was before: not minimized in tray.