I unhooked my PB from everything and took it over to my girlfriends and when I got there and pressed the power button to turn it on rather than getting the "bong" noise I got a loud screeching and now it does it every time I start it up. Has anyone had this happen to them? Should I give Applecare a call and see what they suggest? I just wanted to add that other than at startup the speakers work fine. I am able to listen to music and have absolutely no problems with the speakers.