“AMD-V is not available” even when Virtualization is enabled in the bios [duplicate]

I enabled virtualization in the bios yesterday and the virtual machine worked yesterday. Today, I double checked in the bios and virtualization is still enabled. But the virtual machine is giving me this error when I tried to start it up:

Failed to open a session for the virtual machine Ubuntu 15.04.

AMD-V is not available (VERR_SVM_NO_SVM).

Result Code: E_FAIL (0x80004005)
Component: ConsoleWrap
Interface: IConsole {872da645-4a9b-1727-bee2-5585105b9eed}

What's causing this, and what do I do?

My motherboard is a Gigabyte GA-78LMT-USB3

My CPU is an AMD FX-6300 3.5GHz 6-Core Processor Black Edition

Update: After installing a 32-bit version of Ubuntu on the virtual machine, it worked fine. However, that still doesn't explain why VirtualBox doesn't detect that I have AMD-V, I tried running ubuntu on vmware and that tells me that I have to turn Hyper-V off, so my virtualization is definitely on, it's just that virtualbox does not detect it.

Update 2: Ubuntu launches, but it keeps flickering non-stop; this means that VirtualBox is not detecting my Hyper-V.

Update 3: Hyper-V was installed on the system, Hyper-V apparently causes a conflict between other virtual machines, I'm turning this off now and letting windows restart.

Update 4: IT WORKS!

Make sure Hyper-V is disabled.

This is the command you should run in cmd.exe as an administrator

dism.exe /Online /Disable-Feature:Microsoft-Hyper-V-All

Full instruction set is listed here

http://www.poweronplatforms.com/enable-disable-hyper-v-windows-10-8/