I've been hearing popping sounds coming from the speakers as well as somewhere... deeper. Not sure what's going on exactly but it doesn't sound good. Also, until today my SuperDrive would burn CDs just fine, but not DVDs. Now it won't burn CDs either. As a precautionary measure I've taken all the files off the iMac and put them on my Intel iMac for safe keeping, since that Mac is backed up with Time Machine and the iMac G5 is not.