If you're trying to use Windows XP Mode and Windows Virtual PC on a computer running Windows 7, you might see one of the following error messages saying that your computer doesn't support hardware-assisted virtualization (HAV):
Unable to start Windows Virtual PC because hardware-assisted virtualization is disabled.
Cannot start Windows Virtual PC Host Process. Check the system event log for more details.
Windows Virtual PC cannot start because this computer does not support hardware-assisted virtualization.
An update is available to remove the HAV requirement for using Windows XP Mode and Windows Virtual PC in Windows 7.
You should only install this update if your computer doesn't support HAV. To find out, go to the Windows XP Mode and Windows Virtual PC support website, and then download and run the Hardware-Assisted Virtualization Detection Tool.
This update only applies to Windows XP Mode and Windows Virtual PC (and other virtual machines running Windows XP with Service Pack 3) on a computer running Windows 7. Don't use this update if you're running any other combination of operating systems.
You can download and install the update online from the Microsoft Download Center:
Get the update for supported 32-bit versions of Windows 7
Get the update for supported 64-bit versions of Windows 7
If your computer supports HAV, but HAV is turned off, we recommend that you turn it on in your computer's basic input/output system (BIOS), instead of installing the update. The steps for doing this vary depending on the BIOS manufacturer. For sample instructions on how to do this, go to the Windows XP Mode and Windows Virtual PC support website.
Be careful when changing BIOS settings. The BIOS interface is designed for advanced users, and it's possible to make a change that could prevent your computer from starting correctly. For more information, see BIOS: frequently asked questions.
Article ID: MSW700075