I reinstalled my driver (the latest) and the problem went away. The hardware cursor also started working.
This is an Intel 82830M (intel calls the driver PV14.7, but windows calls it 6.14.10.3889).
The screen with the wireframe plane in the background (mission computer, commodity exchange screens...) lacks overlays -- frames, scrollbars, any kind of boxes -- and simply has free-floating texts. If confirmation boxes are invoked (i.e. to overwrite a savegame), the "Confirm" and "Cancel"...