WD 1TB Caviar Black - constant buzzing noise, Windows 7 not recognizing

Everything was working fine this morning, but came home - turned on the computer and heard a loud buzzing noise.  Booted up windows 7, and the drive is not being recofnized.  Verified that the noise is coming from the hard drive.

Any ideas?

Sounds bad. Download the Datalife Diag software and see what it reports.