8.1 would not install for me either. It would freeze at 'Configuring Device'.
I had to disable a bunch of options on my motherboard (via BIOS) and then it worked.
(After 'downloading / preparing' the update to 8.1 the computer reboots - enter BIOS then and disable onboard bluetooth, usb3, lan and it should work. If not, try also unplugging everything but your mouse / monitor - that's how I got it to work).