Hi everyone, Let me begin with a quick summary: I just switched from Windows to Mac (got a new MacBook Core 2 Duo) and absolutely love OS X. I went to see a tech at the Genius Bar on Tuesday about a few minor issues, and when he examined my computer, he noticed dark shadows in the bottom corners of the display (I noticed them too but was thinking I'd just live with 'em); he and the store manager offered to exchange the MacBook (even though I didn't ask them to, which was nice of them). When I got the replacement MacBook home, I checked the display: perfect! But this replacement has a different issue. Basically, I feel a consistent, minor vibration on the right wristpad and along the top case of the MacBook just to the right of the keyboard. I can also hear something spinning constantly. I figured this must be the hard-drive that's causing the vibration and the spinning noise, or perhaps a fan. The thing is, though, the spinning noise doesn't stop at all unless I put the MacBook to sleep. In addition, the previous MacBook didn't have this issue. Any ideas? I've read online that some MacBooks do have the vibration, but shouldn't the spinning stop from time to time? If this is normal, I can live with it, but I want to make sure that it really is normal. I have noticed that this particular MacBook takes longer to boot up than the previous one.