I've begun to notice problems with my MBP 15" (2007/8) recently. First, it was a noise near the bottom of the monitor (and slightly left) which seems associated with the brightness of the screen when I switch on the computer, but then goes away. More recently, I've noticed that the computer does not go to sleep when left alone as it used to. Bluetooth is inactive, I've checked the energy settings, I've reset PRAM and restarted the SMC. I decided to check the HD to test for problems as I saw this as one potential fix on a forum. Instead, I got this: Now I'm scared and don't know what to do. Help!