Hello @Ricardo Valim
The same issue was reported and solution was provided in the next thread:
System Registry GFlags: Error: 5
https://social.msdn.microsoft.com/Forums/vstudio/en-US/c18c8b04-8185-4a69-af0a-247c6ae17d73/system-registry-gflags-error-5?forum=windbg
I would recommend to check and implement the actions discussed as a first approach.
Hope this helps with your query,
---------
--If the reply is helpful, please Upvote and Accept as answer--