A few days ago, Win 10 (which installed itself without my permission) failed to start, hanging up after a few seconds. Five attempts to restart, including shutting the computer down three times, failed. I couldn't revert to Win 8.1 as the W-10 installation had removed it. The only option was a reset. It does warn ahead of time that it will return the computer to its original build configuration, but I had no idea what a mess it would make. It deleted all the after-market software I had installed (Quicken, Open Office and others) and also a whole slew of Dell support programs. It printed out a full list of what had been deleted, but none were recoverable within the machine. I'm sure glad it left user's data files alone. How do you delete this pile of **** and go to Win 7? That Macintosh looms ever larger in my rear-view mirror!!