What an absolute PITA.
Eventually got the laptop working correctly again.
After waiting about ten minutes I finally got the Event Viewer to load and it eventually displayed the error logs. Lots of DCOM 10010 and 10016 errors reported.
Did a scan with SeaTools for Windows which was clean.
Finally bit the bullet and using the Update and Security/Recovery options rolled the PC back to the previous version of Windows and it is now back to normal.