I know this is going to sound like a crazy question, but I think my MacBook senses when I walk in the room. This is a first gen Intel MacBook, 95% of the time running Windows 7 (yes, this obviously has a bearing on what's happening, so feel free to move this to the Windows on Mac forum). I installed 7 about two months ago. 2 or 3 times I noticed that when the screen was off, and I walked towards the laptop, the screen would turn back on. At first I thought it was the bluetooth on the phone in my pocket, telling the MacBook it was back in range. But 15 minutes ago, the laptop screen came back on, and Bluetooth was off. How the hell does it know I'm close by? Is it possible that the infrared port is being used? The iSight camera is always off. Or the microphone?