Raspberry Pi can't see external hard drive

view story

http://superuser.com – My Raspberry Pi (Model B) can't see my external hard drive. It was working before without a problem, until I disconnected and reconnected the drive. It is a self-powered hard drive. When I put another image on a different SD card the Raspberry Pi can see the hard drive no problem, so there is some sort of configuration issue in the current image on the SD card. Any advice will be gratefully received. (HowTos)