Most electronic remotes use an infrared beam, so errant radio signals from a passing police car, fire truck, helicopter, or motorist won't work the machine.

If it wasn't for the fact that there could be other IR sources in your house (like a TV remote), I ask if you've experienced areas of intense cold, seen blue or green lights in your windows when no one was home, heard gibbering in the wine cellar, eery music during the night, and so on. My guess is that a stray bit of IR did it. Take a peek here for an inside view. Remember that there has to be a received as well as a transmitter, so the stray IR could have come from 'most anywhere. And let's not rule out possible transient problems in the electronic circuits.

Unless, of course, you HAVE seen shadowy figures playing your CDs, late at night?