I realize this is quite the common question, and answers are all over the internet. None are working for me. For several weeks, my black MacBook (2008) has been acting odd. Certain applications won't open, and when I attempt to open them, the computer makes a quiet clicking noise, like the drive is failing. Last week, when trying to boot it, the thing just wouldn't. Stuck on the grey Apple logo screen. Assuming a hard drive problem or failure, I ran the tests. I ran Disk Utility from the Snow Leopard install disk, checked & repaired permissions, checked & repaired disk. All okay. I ran the Apple Hardware Test from the install disk that came with the computer, using the test that runs for an hour or so, and all appears to be fine. The computer won't boot into safe mode. I've tried flashing the PRAM. I doubt I could achieve much through target disk mode, as I've already run Disk Utility. What's left to do? Something doesn't add up here.