PowerPC :: Ibook G4 Not Functioning Right?

ibook G4 running on Mac OSX V. 3.9 It has worked great ever since I bought it but in recent months it has began to act wierd. There is a constant, I guess you could call it grinding, of the motor. It often freezes and the only way to fix it is to shut it down by holding the power button. When I try to turn it on again, it gets to the gray screen with the apple and the gear and just spins and spins and spins until finally it works. Today when I turned it on after it freezing it took about 15 minutes to get away from the grey screen. When it finally did, it took me to the registration page and had me enter all my information again. However, even though everything is reset, my documents and pictures ares still there.