Today, I was downloading a couple of huge files, while also trying to play a 100 MB QuickTime movie, when I heard noises that I wasn't used to hearing from my 12" DVI PowerBook's internal hard drive. These noises were definitely louder, (but not LOUD) and more distinct, and of a different pitch than the usual 'ticks'. It sounded like the disk was struggling a bit. But the thing is I have never heard these noises in the four months that I owned it. After putting the machine to sleep, and waking it up a few hours later and using the computer lightly, these noises seem to be gone. Am I being paranoid, or could there be something wrong with my hard drive? How can I tell?