I've gotten that message 3 or 4 times since I've owned the car... (3 years or so)
Each time I just disconnect and reconnect the battery and problem solved. Last time I had some weirdness with the coolant temp sensor, but after sitting overnight it cleared itself up.
Seems to always happen to me when it's wet out, but yeah I've had it multiple times and both my battery and alternator are strong.
The fact that it sat overnight and went back to normal kinda makes me think water got somewhere that made the car unhapy.
