error VT-x/AMD-V

[pupil]

Hello,

I installed Virtualbox 4.2.6 on my Windows8.

When I tried to install Solaris 11 on the virtualbox, it gives following error,
"VT-x/AMD-V hardware acceleration has been enabled, but is not operational. Your 64-bit guest will fail to detect a 64-bit CPU and will not be able to boot.
Please ensure that you have enabled VT-x/AMD-V properly in the BIOS of your host computer."

Please suggest some solution.

Is it that Solaris 11 not compatible with Virtualbox and that I should instal Solaris 10 or such earlier version?

[noteirak]

First ensure that Hyper-V is disabled or uninstalled in the Windows 8 Features - this will lock the virtualization capabality for exclusive use at boot time, preventing Virtualbox to use it.

If this is already the case :

Please ensure that you have enabled VT-x/AMD-V properly in the BIOS of your host computer."

Moving this to Windows Host