Had a similar problem on a Special Force. Usually it would work correctly but occasionally the solenoid expander board would buzz, and the wrong solenoid would be energized. After ruling out the usual causes I finally found the problem. The fuse clips for the controlled lighting circuit were corroded, and occasionally the voltage would drop. When that happened the solenoid expander board's relay would not engage, it would just buzz. Strangely enough I didn't notice the bulbs dimming when this happened. Replacing the fuse clips solved the problem.