I was "suckered into" installing Win 8.1 "preview" on my new laptop. BIGGEST FREAKIN' MISTAKE I ever made. Absolutely NOTHING except Windows ran after that. I was left with NO CHOICE but to re-format and re-install EVERY LAST PIECE of software I had. If that's Microsoft's idea of a "preview" I don't ever want to see the full version, because it'll be "crap" on steroids.
If you can "roll back" to 8.0, DO IT. If not, you may be screwed like I was, but Win 8.1 is an absolute "train wreck.