I'd like to outline the procedure to install dual booting Windows/Linux on computers with the UEFI security system This abominable bit of malware can be found on recent models produced by HP and Acer etc. It seems to be associated with Windows 8. The required procedure is a departure from that of the straight forward BIOS machines, and following those original procedures will meet with failure. It's not difficult to bypass the UEFI but I struggled with it, spent a frustrating day consulting many difficult and confusing HOWTOs such as this one. I've done installations hundreds of times on pre-UEFI computers. It's possible to follow basically the same procedure once the UEFI has been bypassed. Here's how: Once you switch on the computer, having backed up any precious data in preparation, check very quickly for the key to enter the BIOS configuration. You'll only have a few seconds and there should be a message briefly displayed at the bottom of the screen. It's often F2 or the DELETE key, but it varies from machine to machine. Once in BIOS, a screen something like the following should displayed:
Select the security tab:
And create a supervisor password. It doesn't have to be elaborate. Just ensure it's memorable. Once the password is created, select the boot tab:
Now the 'secure boot' option can be disabled. And the 'UEFI booting' option can be switched to 'legacy BIOS.' The booting sequence should also be altered at this point, so that USB containing the source iso should be given priority over the hard drive. The images used here will almost certainly differ from what is seen on your computer, but that's nothing to worry about. What's important is to 1) give yourself a supervisor password, 2) disable secure booting, 3) switch from UEFI to legacy BIOS, and 4) prioritize USB booting. Press F10 to save the settings. Now the computer is ready for normal installation. Use a 64bit Linux iso on these machines.