My 1197 does similar when trying to set Simulator Position ... It responds very slow at 1st - then the cursor rapidly moves the longer I hold the 4way cursor button ... And the + and - buttons sometimes don't respond when trying to set the Simulator Position ...
This seems to be exacerbated when zoomed out farther on the map ... and not as noticeable if zoomed in closer when moving the cursor to the desired position on the chart ...
I have no explanation for this ...
Rickie