Having somehow lost my previously rather long detailed account, twice, this is a much abbreviated version. Update OK - examine new features - Notifications- Warning corrupt 'C' drive-diagnose and fix? Ok. Very long and went to bed. The dreaded black/grey screen. Various resets/ hard -No go. Laptop Google - well known but not apparently acknowledged my Microsoft. The following were found and proved invaluable. SHIFT +Restart to reboot in W10. Windows symbol+R/ W+L. But there is no working taskbar icons - only Win, time and Malwarebytes, coming and going. Using W+R and L, an extra symbol appeared on the extreme right of the taskbar. Click - Restart- warning message-HOLD down Shift and click Restart to boot into Safe mode- various options. Eventually found revert to previous version. Well why not-Old ver W10 but MS Office suite, CCleaner, Malwarebytes all missing. Ordered to have my breakfast and to go outside to cool off. Eventually connected an external HD and in Win Security and Update, found the last restore point W10 created before installing. Eureka, there was my familiar screen with all components present. Contrary to popular belief F8 does not often work to boot to SMode. Some advice on Google, was to wait until MS sort this out.