First, the likely only real solution is reported in This Read-Only Problem Has Been Solved on My Computer by YPCheng. It is the file takeownership.zip. YPCheng failed to give the link because the MS support person downloaded it to him.
The message Don't be too upset by R. Proffitt is, at once, condescending and self aggrandizing and potentially dangerous for most but the truly knowledgeable. The link shown in his 'advice' gives the standard instructions for attribute changes but does not include Windows 10 in the list of applicable Windows versions. NOTE: This cnet forum is about Windows 10. Not previous versions.
Furthermore, you clearly don't know the real cause for the problem, nor do you understand software even though you state in your post Odd how long you have been involved with computers. So why waste everyone's time without giving the hard, official solution. (As given in YPCeng's message quoted above.) Instead you offer more of the same useless help that is slowly filling this forum. Pros, real pros, would never offer workarounds in a situation like this. That is diddling. Don't diddle around in a major, highly sophisticated, and from the signs of it, fragile OS. That is a BIG No No!
So, pleeeeze . . . don't waste our time with prose designed to impress with huge experience. If and when you have the real solution, directly from MS--just give us the link. Don't bother to translate and impress with your superior computer prowess--just the link, and we'll go there.
Confession: absent knowledge about the MS solution above, the takeownership.zip file, I went ahead and used the homegroup solution and that seems to work, albeit with some reverses. In other words in my impatience I may have messed up my system in ways I may yet have to discover. Talk about not following my own better knowledge/advice. 