Windows 8 Guest, CPU Speed

[AdrianSB]

I have a problem with Virtual Box (4.2.6) on Mac OS X (10.8.2) running a windows 8 guest.

I currently have the consumer preview running and want to upgrade it to Windows 8 Pro. However, the upgrade advisor tells me the CPU speed
is too low ( < 1 GHz) - checking the control panel in windows I see... E8335 2.93 GHz 755 MHz. So I assume windows is seeing the second value and refusing.

I have the acceleration shown as "VT-x/AMD-V, Nested Paging, PAE/NX" in the System part of the machine configuration and if I try to edit this, I find a box with "Extended Features: Enable PAE/NX" greyed out and ticked in the System->Processor menu.

Any ideas?