I have an LG lcd monitor that I've had for several months and use with a new mac mini. I've noticed an occasional cracking or popping sound that seems to be coming from the monitor when it is turned on for more than several hours. Could this be a heat issue such as the plastic expanding? The sound could be coming from my computer speakers but I hear it when the speakers are shut off. It never makes the noise unless turned on for 4-6 hours.