I have a brand new clean machine with Windows 7 Professional 64bit and I've installed the patch that adds Windows Virtual PC (Windows6.1-KB958559-x64). I then go to Windows Virtual PC, create a new Virtual Machine. As soon as go to settings and try to map the VM DVD drive to the host's DVD drive I get "File may be in use by another process or you may not have sufficient access privilege". I am an administrator in that box... What am I missing?
For me, a similar problem was resolved by eliminating RDP from the equation.
I use a laptop and a desktop machine, with the desktop hosting a virtual machine. I was trying to share my desktop's DVD drive with its virtual machine and getting the same error message; however, I was doing all of this connected from laptop to desktop via a Remote Desktop Connection.
Accessing the desktop machine in person (and then booting the virtual machine directly) gains me the sufficient access privileges.