Troubleshooting Hyper-V

Applies To: Windows Server 2008, Windows Virtualization

This topic covers some common issues you may encounter when using Hyper-V™. For more in-depth troubleshooting information based on Hyper-V events, see the Hyper-V troubleshooting content at the Windows Server® 2008 TechCenter ( To search the Knowledge Base for articles about Hyper-V, see Help and Support at

What problem are you having?

I installed the Hyper-V role and can create or import a virtual machine, but I can’t start the virtual machine.

Cause: The hypervisor is not running. You can check the Hyper-V Hypervisor event log to determine whether the hypervisor is running.

Solution: The physical computer must meet specific hardware requirements to run the hypervisor. For more information, see Hyper-V Installation Prerequisites. If the computer does not meet the requirements, you will not be able to use that computer to run virtual machines. If the computer meets the requirements and the hypervisor is not running, you might need to enable the settings for hardware-assisted virtualization and hardware data execution protection in the BIOS. If you modify these settings, you must turn off the power to the computer and then turn it back on. Restarting the computer does not apply the changes to the settings.

Cause: The virtual disk that serves as the system disk is attached to a SCSI controller.

Solution: Attach the system disk to an IDE controller. For instructions, see Configure Disks and Storage

Cause: The virtual machine is configured to use a physical CD or DVD as the installation media, and the physical drive is in use.

Solution: A physical CD or DVD drive can be accessed by only one virtual machine at a time. Disconnect the CD or DVD from the other machine and try again.

Each time I shut down a virtual machine, it restarts.

Cause: The virtual machine is highly available. In other words, it is part of a cluster.

Solution: Use the Failover Clustering feature to manage the virtual machine. To turn off the virtual machine, you must modify the properties of the virtual machine resource and take the virtual machine offline. From the Failover Management snap-in, navigate to the virtual machine resource. Right-click Properties and then click the Offline Actions tab. Choose the appropriate action and then take the virtual machine resource offline. The actions are:

  • Turn Off

  • Save

  • Shut Down

  • Shut Down (Force)


Changing the Offline Action affects the behavior of the virtual machine if a failover occurs. For example, if you choose a shutdown action and a failover occurs, the virtual machine will shut down instead of fail over to another node.

I cannot perform a network-based installation of a guest operating system.

Cause: The virtual machine is using a network adapter instead of a legacy network adapter, or the legacy network adapter is not connected to an appropriate external network.

Solution: Ensure that the virtual machine is configured with a legacy network adapter that is connected to an external network which offers installation services. For instructions about configuring network adapters, see Configure Networking.

A virtual machine pauses automatically.

Cause: A virtual machine will be paused automatically when the volume on which snapshots or virtual hard disks are stored runs out of available storage.

Solution: Create additional space on the drive by deleting unused data. For example, if you do not need to keep some of the snapshots, you can delete the snapshots individually, or to delete all of the snapshots, export the virtual machine and then import the virtual machine.

When I use Virtual Machine Connection, the mouse pointer appears as a dot or the mouse pointer is stuck in the virtual machine window.

Cause: Integration services are not installed in the guest operating system.

Solution: If the guest operating system is supported, integrations services are available for that operating system. Install the integration services to improve mouse integration. For instructions, see Install a Guest Operating System. If the guest operating system is not supported, you can use a key combination to move the mouse out of the virtual machine window. The default key combination is Ctrl+Alt+Left arrow.

When I try to control a virtual machine, I cannot use the mouse and keyboard input behaves erratically. I am using Remote Desktop Connection to connect to a server running Hyper-V.

Cause: When you use Hyper-V Manager to connect to a virtual machine, Virtual Machine Connection provides the connection to the virtual machine. However, use of Virtual Machine Connection within a Remote Desktop Connection session is not supported. As a result, lack of mouse functionality and erratic keyboard input is expected behavior.

Solution: Avoid using Virtual Machine Connection within a Remote Desktop Connection session. There are several ways you can accomplish this:

  • Establish a Remote Desktop session directly to the virtual machine.

  • Log on to the console of the server running Hyper-V and then use Virtual Machine Connection to connect to the virtual machine.

  • On a computer running Windows Server 2008 or Windows Vista® with Service Pack 1 (SP1), install Virtual Machine Connection on the computer and establish a Virtual Machine Connection session to the virtual machine.

When I open Device Manager in the guest operating system, some devices are listed as unknown devices.

Cause: Device Manager does not recognize devices that are optimized for use in virtual machines that are run using Hyper-V until integration services are installed.

Solution: If the guest operating system is supported, integrations services are available for that operating system. After you install the integration services, Device Manager will recognize the devices. For instructions, see Install a Guest Operating System. If the guest operating system is not supported, the devices will be usable but will remain listed as unknown devices in Device Manager.

I want to monitor the performance of a virtual machine, but the processor information displayed in Task Manager does not show the processor resources being used by the virtual machine.

Cause: Task Manager does not display CPU information for virtual machines.

Solution: To view CPU usage information for virtual machines running on a Hyper-V server, use Performance and Reliability Monitor to view the data from Hyper-V performance counters. To open Performance and Reliability Monitor, click Start, click Run, and then type perfmon.