I've been running a Windows Server 2012 VM on a Windows 8 64 bit host using VirtualBox 4.2.18 successfully. After upgrading to VirtualBox 4.3.0, the VM fails to start up because it stated that it does not detect a 64 bit processor.

The version drop down also does not show any of the 64 bit versions as it did in earlier versions.

I have checked the BIOS settings of my Dell Latitude E6530, and the Intel Virtualization Technology, VT for Direct I/O, & Trusted Execution options are enabled.

Is there a way to revive my old 64 bit VMs or do I need to wait for a maintenance release of VirtualBox?

Any help would be greatly appreciated.

  • You don't have to wait. I would download a previous version for the time being. – Ramhound Oct 18 '13 at 13:01
  • re-install virtual box should work. ( i mean make sure you get 64-bit version ). – user218473 Oct 18 '13 at 13:10
  • There is only one install for it and it includes both 32 & 64 bit. I also tried installing the previous version, but the damage is done, the VM has the same issue now. I will give it one more try however. Thanks – Raybiez Oct 18 '13 at 13:18

As it turned out, I have certain Hyper-V enabled on my Windows 8 Host machine which disabled all the 64 bit options. Disabling it, resolved my problem.

  • That's exactly what I was looking for. +1 for clear question topic that makes it easy to find. BTW, to disable Hyper-V, search the start menu for "Turn Windows features on and off" – mloskot Jun 19 '14 at 9:49

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