Failed to start Virtual Machine

Hi all,

I create a Ubuntu Server 14.04 LTS Virtual Machine. Then I create a Remote Desktop (RDP) to the Ubuntu VM using RDP.

Everything is working, but when I stop and then re-start the VM tI receive the following message:

"Failed to start virtual machine 'AndreaUbuntu'. Error: error"

How is it possible that? Where is the problem?

Thanks for your help,

Andrea