I recently sent my powerbook in for repairs. It was crashing with crazy screen artifacts/anomolies. I also menitoned to them that the hard drive would make constant noise at times, most frequently when web browsing. I got it back and they had replaced the display, logic board and HD. Now it doesn't crash which is good. And the drive noises were completely gone. I have noticed recently that they are coming back though. On certain webpages the drive which just start making noise, only to stop when i click and hold the mouse button down... Very annoying sound in a quiet room. Is this a normal thing or do I have some other problem?