My 800XL and 1050 were working fine until I disconnected them and moved them to another room in my house...
The white and black switches are both set to the left.
I power on the drive and it spins for a second. I put in a disk and close the door and it spins for about 10 seconds. When I power on the computer it just goes to the "Ready" prompt. If I hold "Option" and let go of it when the blue screen comes on it still just goes to "Ready".
Basically it seems like the computer is not communicating with the drive.
Drive was NIB when I got it. It has only been used about 50 times total in it's life. I literally disconnected it and walked it to the next room without dropping it or anything.