virtualbox.org

Hi,

I have problem with virtual box. When I install update on Windows 8.1, VM throw the error, that it can support 64-bit processors and use only 32 bit. So now every system what I want emulate must by 32-bit, but before on Windows 8 was possible host 64-bit systems.

Make sure you select a 64bit template in <vm settings>|General|Basic|Version, e.g. for a Win7-64 VM be sure this says "Windows 7 (64 bit)" and does not just say "Windows 7".

Also, on Windows 8 hosts you must ensure that Hyper-v is not running in the background. However this issue (if present) would have been present before the VirtualBox update too, so cannot have been caused by updating.

Try disabling the Windows feature "Hyper-V". It solved the problem for me.