Since last week I started migrating all my HyperV VM's into Sun's Virtual Box.
All my VMs migrated without a problem (after I learned I have to completely remove the HyperV before the virtual box would start...) except for one.
Trying to start it gave me an error: "fatal no bootable medium found system halted virtualbox" and I could not even use the VHD to format and reinstall it!
This one was a virtual windows 2008, 64bit with MOSS 2010 installed.
It was my only win2008 and my only 64bit VM - so I assumed this was the problem...
But, as it so happen, this was also the only VM I created in HyperV! All others were migrated from VPC or Virtual Server editions.
So, after a lot of research, formatting, copying, pasting I found the solution.
It appears that HyperV created VMs are not the same as VPC ones, and Sun VirtualBox does not recognize the HyperV VHDs correctly.
The quick and easy fix (which I didn't believe would work but did!) was to install VPC and use the VPC VHD wizard utility to compact the HyperV VHD.
Don't ask me why, but it did the trick and now my VHD is bootable in Sun VirtualBox!
Since I did not found any post on that matter anywhere I thought this might be handy for some of you.