Try checking the battery, many electrical gremlins come out to play when batteries get tired. Leave it for a couple of hours and measure the voltage across the terminals.
Anything less than 12.3 / 12.25 V and I'd be considering a change, definitely if you've got less than 12.1 V. Also worth checking the alternator afterwards - start up and measure again, you're looking for 13.2 - 14.4 V. If you've got less than that the alternator could be the cause of the low battery.