Another thing that happened a year or two ago that might be a factor in PC settings being screwed up is something that was put on before we even got the Dell Optiplex 780. If you have one of those, this might be messing up a couple of things.
The problem was it kept tossing the updates, some critical such as some Flash updates, for example it was throwing out everything beyond version 8, nFS requires version 9 at minimum. It was also screwing up the FHC Portal page as that needs certain certificates to run properly and get you into some of the pay sites that we get at FHCs and do that properly.
Then I found it. A small little program hidden in the list of programs in the 'add/remove programs' area of control panel. This was called 'Microsoft User Hive Cleanup Service'. Once I uninstalled that, we never had any problems again of the kind I have described.