virtualbox.org

I use a couple of virtual machines to make sure that my main computer doesn't get infected when I'm opening risky files and such.

I decided to reinstall Windows 8.1 64bit earlier today and my Virtual Machines were working absolutely fine.
I wanted to setup my Virtual Machines again on my new fresh operating system and I got this error.

Failed to enable and lock VT-x features.
(VERR_MNX_MSGR_LOCKING_FAILED)

Result Code:
E_FAIL (0x80004005)
Component:
Console
Interface:
IConsole {1968b7d3-e3bf-4ceb-99e0-cb7c913317bb}

I'm using 16GB of DDR3 RAM
i5 4690k.

I haven't changed any BIOS settings at all and there's no reason too if it was working fine before without any changes.

Is there any drivers that I could be missing that might be causing this issue as I've only really downloaded graphics drivers.

Make sure Hyper-v is not running.