When using Windows Repair 3.9.17 to reset registry and file permissions on Win 10 Pro, x64, my default programs for browsing and email changed from Firefox and Thunderbird to MS Edge and nothing. This has happened several times. Is this intended behavior? It doesn't make sense to me. I ran in safe mode, admin account, and after doing chkdsk.
Incidentally, Win 10 has known problems allowing users to set non-Windows default programs, which I am now struggling to fix. That would be a great repair to include in future versions.