Not sure of your setup but does your USB cable run along side any power cables? It may be that if the light is making a lot of noise, that the noise is being picked up by the USB cable if it runs parallel with a power cable. This shouldn't effect it but may indicate you have a bad or poor USB cable itself.
You can try to relocate the cable to the CM15A to see if this helps. I run 2 USB extensions on my controller and every now and then the AHP software pops up an error saying it lost communications. and asks if I want to download to the controller. Also inspect the USB plug ends for any damage. Be sure to unplug them and then plug them back in. Could be a dirty or bad plug connection.