I would look for something new (or something moved to a different outlet) on the same circuit as the CM15A. Also CFL bulbs are known to get noisy when they age. That causes some of the "drives me nuts" problems as nothing has changed or been added in the house, but a CFL somewhere in the mix is now cranking out more noise. I currently have a wierd one I am trying to troubleshoot. I suspect I have noise problems generated by a Panasonic five station cordless phone system with switching power supplies on each charging station. When intalled in November they were not a problem, but now may be. I just have not had the time to determine if only one charger is becoming noisy, or all of them....sigh. Like one members signature states: "X10, yesterday it worked, today it doesn't."