As you probably know, if you want to use the Windows Phone emulator in Visual Studio, because it runs on a Hyper-V virtual machine, you need to turn on all the Hyper-V features in Windows, from the control panel->Turn Windows features on or off.

Turn on Hyper-V features

If you have the Hyper-V Platform item greyed, to enable it you have to enable Virtualization on BIOS. To do that your PC, first of all, must have a microprocessor that support the virtualization technology and then enable it in the BIOS.

Unfortunately I found in my new HP EliteBook (identify it), some of the BIOS features disabled (greyed) and in particular that related to System Configuration->Virtualization Technology. I don’t know why but to have all the features enabled (not greyed) you HAVE to set the set the bios administrator password in the Security tab after having accessed in the BIOS pages (F10) as a guest user!! (see this link for more details) NOTE: if do not remember the BIOS password the only way seems to erase it, as explained here:

• Turn OFF the computer and unplug the power cord.
• Locate the jumper labeled CLEAR P.W.
• Move the jumper on jumper PSWD to pins 3-1.
• Wait approximately 10 seconds and then return the jumper to pins 5-3.
• Plug in the power cord and turn ON the computer.
• Hold down the F10 key during the startup process to enter BIOS setup. You will not be asked for a password.
• Diagrams can be found on the “motherboard specs” page for your computer.

To update BIOS see here.

For further details on how to set Virtualization on that PC, you can see alo this link.
This link can be useful too.