When I drive at night in the rain, sometimes both my instrument panel lights and wipers go out at the same time, seemingly randomly. What would likely cause this? Could it be a problem with the battery, or just a loose wire somewhere?
Problems like this are usually because of a loose ground wire somewhere. Intermittent electrical failures are amongst the hardest problems to diagnose. Without further information (like the make/model/year of the vehicle), it is really hard to help you diagnose this further.