Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

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.

share|improve this question
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
up vote 1 down vote accepted

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.

share|improve this answer
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

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.