Hi Dave,
The error you're seeing would normally suggest a failed/failing drive but if you're experiencing this on multiple units I would begin to wonder whether it's docking correctly (maybe a pin is broken etc). Start your machine and take a trip into the BIOS; check the drive is being seen (a failing drive often won't show up, a disconnected drive certainly won't!), and make sure its reporting the correct size etc. While you're there take a wander round the BIOS to make sure nothing unusual is going on.
There is of course the possibility that both drives you're trying are failed; have you tried putting your original drive in another laptop? Did that work?
What model machine do you have? Have you performed any other diagnostics?
Dan
