Hyper-V Errors

I've been using Hyper-V for my virtualisation requirements lately, and in general it's been very smooth. I'd love the memory-sharing of ESX given I'm running a dev/test box, not a prod server, but so be it.

I just went to kick up a new VM, attached the DVD Drive, and promptly had the following spat at me:

'MachineName' failed to start. Microsoft Emulated IDE Controller (nasty guid) : Failed to power on with Error 'The process cannot access the file because it is being used by another process'.
Failed to open attachment 'E:'.


Ouch.

Nothing else on the host server was using the DVD drive, but one of the other VM's still had the physical drive assigned to it. Disconnecting it allowed the new VM to start straight away.

Attempting to re-attach the drive to the existing VM then threw a very similar error.

Moral of the story: Apparently only one(1) VM can have access to the physical CD/DVD drive at a time.

Hope this is sufficiently detailed to help out the next poor sap that runs into this.