I recently upgraded my laptop to Windows 8 to take advantage of Hyper-V in the management of my virtual machines.

To get better performance using SharePoint, I bought an SSD and I moved my vhds to the new disk. At this point, I have to change the path of the VHD virtual machine settings and when Itry to do this, I got this error: "Can not add device virtual hard disk."

I tried to change the virtual hard disk file permission, but the error was alsways there.

To resolve this error, one must perform the following steps

• Mount the VHD (double click on the file)
• into disk management tool, put offline the disk
  
• into virtual machine settings, remove the link to the old path of vhd, add a new physical hard disk and select the offline disk
  

Et voila, The system can manipulate the vhds on the SSD disk :D