GkSpk

If you are getting the VirtualBox can’t operate in VMX root mode error dialog shown below …

… it is because you have the kvm and kvm_intel kernel modules enabled. You will need to unload them using the following commands:

sudo modprobe -r kvm_intel
sudo modprobe -r kvm


You should now be able to start your Virtual Machine.

If you want a permanent solution, you need to disable full virtualisation for qemu/kvm using the Boot-up manager. You can do so by following these steps.

1. Install the Boot-up Manager:

You can do this via the Software Center, where you can find it in the System Tools section:

Alternatively, you can install it by typing the following in a console:

sudo apt-get install bum

2. Start the Boot-up manager from the System > Administration menu.

3. Untick Full virtualization on i386 and amd64 hardware and click Apply.

Note: VirtualBox will still run under full virtualisation provided your system supports it.