Why VirtualBox won't give me option to create 64 bits guest?

[nosachamos]

My host is x64 bits Windows 8.1.

I downloaded the latest Virtual Box (4.3) and I'm trying to create a VM with a 64 bits Ubuntu OS (ubuntu-12.04.3-desktop-amd64).

When I go to New VM wizard, it doesn't give me option to select "Ubuntu (x64)" as I have seen in other people's screenshots, only just "Ubuntu". As a result, the ISO can't boot. I tried in another PC and Virtual Box gives the x64 variants to most listed OS...

Control Panel shows x64 OS, x64 processor. My host laptop is a Sony Vaio VPCZ22UGX/N, Intel® Core™ i7-2640M processor. CPUz shows Vx-t is available on my processor, of course.

Here is what I tried so far:

• I enabled IO APIC as required in the docs.
  
  I have virtualization enabled in the BIOS. It works fine in VMware.
  
  I also tried running the command:

  Code: Select all

  VBoxManage modifyvm [vmname] --longmode on

for that VM, but no change.. I think the issue is really that I can't select x64 variant of the Ubuntu OS for that VM. Other people seem to indicate that's a requirement, but I don't get that option for some reason.

I spent a lot of time and can't find what's wrong... Anyone knows what could be missing here?

Thank you very much!!

Eduardo

[Martin]

You probabely have Hyper-V active which blocks VT-x

[nosachamos]

Hi there!
Thanks for the reply!

I checked and the Hyper-V feature is not installed on my Windows. I had VMware installed, so I uninstalled it completely and still I'm getting the same results.

Any other ideas on what I could try?

Thanks!!
Eduardo