A few possibilities exist. I would first check all the connections, and wiggle all the connectors and plugs to see if any one of them is causing it including the power cable. Also try to play with the ON/OFF/Volume switch to see if that's intermittent. Second, for quick isolation of the problem I would connect them to another PC - did the clicking and flickering go away? If it did, then your PC's audio circuitry is causing it - possibilities: defective audio card, or Motherboard (MB) if it has integrated audio, bad connections on MB or audio card, if you're also using analog audio connections going from the back of your CD/DVD RW to the audio card/MB then remove those wires and see if that problem goes away - those wires are notorious for picking up all kinds of noise and feeding that noise to your audio controller. One other thing to try is to completely uninstall and reinstall the audio drivers or even try a different revision.