My desktop system is in an update error loop (0xC1900101-0x20017) that apparently has no solution. Win 10 tries to update, reboots, fails without warning, reboots. I have to run a fortunately free boot disk which removes the attempted update, but certainly doesn't solve the basic problem. "Disconnect all external devices" .. yeah, fine, no improvement. So I'm stuck at Build 10074, and wish I could figure how to stop all updates entirely! (Oh, and trying to reinstall Win10 Pro Insider Preview from an .iso image doesn't work either.) Talk about being screwed .. and it worked so well too, until that update. Time to wipe and reinstall, I guess. Or just drop back to my Win 7 (fortunately saved on a separate hard drive) and wait for the official Win10 release.