I always back up my runtime folder in this way every Month but for other reasons, mainly if I was burgled or my PC broke big time or I had a fire in the house and my PC got burnt [sob!].

Never had the issue you talk about though!

I did have an issue where it wouldn't find textures that it had found many times before but a quick delete of the prefs and restting them did the trick on that occasion!!

 

Injustice will be avenged.
Cofiwch Dryweryn.