Problem-Preferences have trashed themselves

I opened Nuendo today for the first time in 4 days after taking some time off.
The preferences seemed to have “trashed” themselves.
My recent projects list - Empty
My default template opened with different settings, for example the mixer height was different.
Control Room - Disabled (even though the template has it on)
Default Track Colors - RESET
Other preferences, have also been reset, track coloring method, meter colors.
All Midi Devices- Missing
Eucon Adapter- Missing from the list- had to re-enable it.

No changes on the PC, it has been off for 4 days.

If anyone has any ideas on why this could have happened, please chime in.

Nuendo has always been rock solid for me, but this is unsettling.

Had exactly the same thing happen here last week on 5.5.5. Lost all the vst connections, control room. Project lists empty, macros gone etc… Of course I couldn’t find my preferences backup, so had to rebuild from scratch! No idea why this happened, all ok one day and disaster the next.

It would be good to hear if anyone else has had this experience, and if it’s happening in V6

Yes this was Nuendo 6.
It is the first time this has ever happened with any version for me. Strange that only some of the preferences were affected.

This has happened to me on N5 and N 5.5. I always keep a backup now.