Well, I suppose my Geneve is getting old. I hoped to finish everything in MAME before its time has come, but the first symptom showed up yesterday.
The right mouse button is reported to be pressed rapidly when it is not. In my Fractals program, the right mouse button is used to show the menu line with the pull-down menus, and now this line is flickering. Also, I tried a test program for the mouse, and the "right button" text flickers on the screen.
Too bad this still happens when I unplug the mouse.
When I press the button, the flickering stops, and the button is correctly detected. So it seems as if the unpressed state has become unstable.
The right mouse button is checked by the v9938 (unlike the left button which is checked via CRU). My theory is that the pull-up resistor on the Geneve board has gone bad. At least this would be the preferred explanation, since I could fix this with a soldering iron. Other ideas?