I updated Virtualbox on an Intel-based tablet and tried to boot a copy of an Ubuntu virtual machine. I got the message:
VT-x/AMD-v hardware acceleration is not available on your system. Your 64-bit guest will fail to detect a 64-bit CPU and will not be able to boot.
I’ve run Virtualbox on the tablet before but in the interim it’s been updated to Windows 10 and has had some compatibility BIOS and chipset updates. So I checked the BIOS to make sure Intel Virtualisation support was turned on – it was.
A forum post suggested that enabling the Hyper-V feature within Windows will by default disable VT-x for everything else. I checked in Programs and Features and the Hyper-V Windows feature was indeed enabled – I vaguely recall enabling it for a lab exercise. I disabled it and rebooted – the virtual machine now boots.