My Powerbook G4 recently started doing the HD clicking and squealling noise. So I changed the HD and everything worked great for about a day. Now there is a new Humming/Ticking noise coming from the area where you plug the power supply in. If i tap in that area, it will go away for a couple minutes and then it comes back again. Sometimes it will just go away on it's own for a few minutes too. It doesn't change if I unplug the power or anything. Has anyone else had this problem or know what this is? It is driving me absolutely insane! Please help.