I have used a Toshiba Satellite laptop for 14 months. About a month ago, the built-in speakers (harman/kardon) started to echo. Any external speaker connected to the computer also produces an echo. My computer uses a Realtek AC97 audio device. I've looked through the Net for an answer but to no avail. I've searched my computer's system regarding this audio problem for my laptop but can't see a solution. I'm using Windows XP and was told by one of...