Last night during a World of Warcraft adventure, my trusty Powerbook of about four years started making a noise something like a small, accelerating race car. As far as I can tell, the sound was coming from the upper left area of the laptop. In a panic, I immediately shut the machine off and didn't use it for the remainder of the evening. That was the first time that had ever happened, and I've been playing Warcraft on this computer for years. Nothing out of the ordinary. I tried to play again earlier today, and was successful for about an hour before the noise started again. I wasn't able to find much through Google other than suggestions to try AppleJack, which I did. It found nothing, or was supposedly able to repair any problems. I then used my OS X install disc to run a hardware test, which also came up completely negative The funny thing is, during the hardware test while it was testing the logic board, it made the noise for a few seconds, then moved on to other areas of the computer. Any ideas? I'm dead broke and hoping I don't have to invest in anything too spendy... I posted this on the Apple support board and got an answer, but they said it was most likely the cooling fan going into overdrive from me putting the machine through above-everyday use. The thing is, that IS everyday use for me. It's not getting too hot...I have a temperature monitor installed.