1. I had been an avid follower of VMWARE until recently wherein I have shifted my loyalties to VIRTUAL BOX....simple,easy....and the best part is that it is OPENSOURCE.One problem that I often used to face was that when I copied a VDI file from one place to another...it used to give me a message as shown in the screen shot below that said something like " Failed to open the hardddisk F:\....\.....vdi.So I used to keep trying ways and means but that remained unsolved.But there is a single command line solution to this that goes like this...(also shown in the screen shot).Goto the command prompt first as administrator.
Goto the folder C:\Program Files\Oracle\VirtualBox by typing
c:\>cd C:\Program Files\Oracle\VirtualBox
and then type
C:\Program Files\Oracle\VirtualBox>VBoxManage.exe internalcommands sethduuid "h:\path to the vdi folder\yourvdifilename.vdi"
and this should give a message similar to this
(CLICK ON IMAGE TO ENLARGE)
thats it...now open...u should not get the message!!!