LL6.0 installs but after update get X.509 error @boot; LL6.6 install screws PC

[Alan_Wilts]

Well back to square 1.
I again booted to LL 6.6 desktop and reformatted my data partition to NTFS and restarted the laptop. Again I get the X.509 error followed by going into emergency mode whereas before the X.509 would be followed by a filesystem check and eventual desktop.

Code:

[ 0.998701 ] Integrity Problem loading X.509 certificate -65
Your are in emergency mode. After logging in type "journalctl -xb" to view system logs.
"journalctl -reboot" to reboot. "journalctl -default" or "exit" to boot into default mode.
Press Enter for maintenance (or press Control-D to continue)

Control-D doesn't ignore the problem and the PC is stuck.

I booted a USB stick into LL 6.6 Live and change the partition format back to ext4 but a reboot just repeats the above.

Looks like another install but without changing the shared data partition to NTFS, so no sharing with Windows.