I wanted to connect to one of my Hyper-V virtual machines and got this error:
Checking the Internet, I found this article: http://support.microsoft.com/kb/967902/en-us
What should I say, it worked 
Here is what to do if you use Hyper-V RC0 or RC1 and want to update to Hyper-V RTM. I did this recently with my server.
Done.
By the way: I did not need to reactivate my virtual machines.
You can download the update (final release) here: http://www.microsoft.com/downloads/details.aspx?FamilyId=F3AB3D4B-63C8-4424-A738-BADED34D24ED&displaylang=en
As usually, saved states and with that snapshots cannot be updated to the final release: http://support.microsoft.com/kb/950050/en-us/
I will update my Windows Server 2008 and give you some details about the process very soon.
I just heard from a colleague that Hyper-V RC1 is available for download.
You can get it here:
Windows Server 2008 x64 Hyper-V RC1 Update – KB950049
Windows Server 2008 x86 Hyper-V RC1 Update – KB950049
Attention:
The saved states made with Hyper-V RC0 do not work with RC1. The snapshots contain saved states, so they won’t work, too.
I will install the RC1 on my test notebook and share the experiences very soon.
See the Team Blog, too: http://blogs.technet.com/virtualization/archive/2008/05/20/hyper-v-rc1-release-available-on-microsoft-download-center.aspx
Okay, you have used Virtual Server for your virtual machines. Now you have Hyper-V and naturally you do not want to reinstall every machine from scratch.
Here is how you can migrate your old VHDs to Hyper-V:
1. Be sure that you backup your virtual hard disk files (VHDs)
2. Uninstall the Microsoft Virtual Machine Additions
3. If you have no Virtual Server environment to deinstall the Virtual Machine Additions, you can install Virtual Server on Windows Server 2008. Here is what you need:
(If you have uninstalled the Microsoft Virtual Machine Additions, you can continue with step 10)
4. Install Virtual Server 2005 R2 with SP1:
5. Because the Hypervisor of Windows Server 2008 makes the emulated drivers of Virtual Server virtual machines very slow, you should disable the Hypervisor as long as you want to use Virtual Server. This is not just a setting or driver, you have to boot Windows Server 2008 without the Hypervisor. You have to create a second boot entry:
bcdedit /copy {current} /d “Microsoft Windows Server 2008 – for Virtual Server”
bcdedit /set {Identifier} hypervisorlaunchtype off
The first command copies the current boot configuration to a new one called “Microsoft Windows Server 2008 – for Virtual Server”:
The second command turns the Hypervisor for the new boot entry off:
6. Now you have to restart your server, choose the new boot entry to boot it without the Hypervisor.
7. Okay, now as you are back we can configure the new virtual machine wit the old VHD in Virtual Server:
6. Turn the Virtual Machine Remote Control (VMRC) Server on:
7. Connect to the the running virtual machine with the Virtual Machine Remote Control Client:
8. Deinstall the Microsoft Virtual Machine Additions and restart the virtual machine:
9. After the virtual machine is rebooted, you can shut it down and restart Windows Server 2008 with the Hypervisor.
(You can continue here from step 2 when you have uninstalled the Microsoft Virtual Machine Additions)
10. Install Hyper-V, as mentioned in one of my earlier posts.
11. Create a new virtual machine in Hyper-V:
12. Start the new Hyper-V virtual machine.
13. Perhaps you have to activate Windows, because the Hardware has changed due to the Hypervisor:
14. Insert the Services Setup Integration Disk (If your virtual machine is Windows Server 2008 install Hyper-V RC0 or newer in it):
15. Update the Hardware Abstraction Layer:
16. After the HAL update and a reboot the device drivers are installed:
17. Reboot the Virtual Machine:
18. You have to configure the TCP/IP settings. This could be the reason why a migrated domain controller can take a very long time (15 minutes and more) to boot:
That was it, have fun with your migrated machines!
Everyone is using Hyper-V for testing purposes and you want it, too? Read along!
Hyper-V, the new virtualization technique from Microsoft is a built-in component of Windows Server 2008 (not in Web and Itanium Edition, see http://www.microsoft.com/windowsserver2008/en/us/compare-features.aspx). So you cannot just install a program like Virtual PC or Virtual Server, you have to install Windows Server 2008 on a computer which supports Hyper-V.
There are two main hardware requirements for Hyper-V:
1. Processor with built-in virtual machine support (Intel VT, AMD-V)
2. Data Execution Prevention (DEP)
Just take a look into your BIOS if there is any virtualization setting. You have to enable it. Most recent systems have this feature, even notebooks.
Okay, you have the proper hardware and you want to dive into Hyper-V, so let’s start:
I assume that you have installed Windows Server 2008 already and therefore I will start with the installation of Hyper-V. At the moment, Hyper-V is RC0 (Release Candidate 0). It is not final yet and it is not supported by Microsoft at this time. But do not worry, a lot of people have made a very good experience with it, including me. You have to download and install the RC0 version of Hyper-V, because the version that is shipped with Windows Server 2008 is just a beta and you should not use that.
You can find the RC0 here:
http://support.microsoft.com/kb/949219/en-us
Update: In the meanwhile, Hyper-V RC1 was released:
Windows Server 2008 x64 Hyper-V RC1 Update – KB950049
Windows Server 2008 x86 Hyper-V RC1 Update – KB950049
After the installation of the RC0, you can add the Hyper-V Role with the Server Manager:
(on my PC the role was already installed)
After a reboot, you are ready to start.
The next steps, creation, migration and using virtual machines are covered in later posts.