My PC is a laptop which I sometimes use in a docking station and with a monitor. That monitor has a bigger resolution than the LCD of the laptop. While I normally close all programs before undocking the laptop, it is quite possible that one time I forgot that (or the PC crashed or whatever) while the Simple User Interface was in a position which was on-screen for the monitor, but off-screen for the LCD. So you could be quite right (again! :)).

I just noted that I still have a related problem:

When I move the mouse-pointer over the buttons etc. of the Simple User Interface, I no longer get the little help popups which display what the buttons do. Is there a setting for that?