Bugcheck (bluescreen) in Windows 7 Beta guest when running in Virtual PC 2007 or Virtual Server 2005

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First thing i would check if i hit this bugcheck would be this dialog

Hardware Assisted Virtualization not present

If you see the text as shown in the above image that says "Hardware-assisted Virtualization is not available on this computer" then most probably the Additions build installed on your Virtual Machine is not 13.820. Upgrading to this build will solve the problem of the bugcheck.

How to uninstall Additions? My VM will just not boot.

  • Boot the VM into safe mode
  • Uninstall Additions (if that fails delete vmsrvc.sys from %windir%\system32\drivers)
  • Reboot
  • Install Additions build 13.820 (You will need to install Virtual PC 2007 SP1 and use Additions that is installed in that build). For Virtual Server you need to install the update for W2K8 etc from here.

 

Note: If Hardware Assisted Virtualization is not available on your machine, the Win 7 VM would run really slow and the CPU consumption would be high too. I would recommend you check in the BIOS if this option is available there.

 

Technical Explanation:

When Hardware-assisted virtualization is not available, Additions patches the OS kernel to make it perform well inside a Virtual Machine. This patching is OS specific. Since Windows 7 is a new OS the older additions would not be able to patch it. Build version 13.820 has fixes that atleast allow Windows 7 to run (albeit no patches so bad performance), earlier additions cause Windows 7 to blue screen. Recent processors have enhancements that allow OS's in Virtual Machine to run with minimal intervention. This results in better performace even without patches.