Not sure if the question has arisen in this form before. I've just upgraded to Windows10 on my desktop (an HP PAvilion23) and found that file permissions were changed to read/execute; writing and updating not allowed. It's possible to rest permissions easily enough, using the Properties option on folders, and I've done that. I clears the problem for the session, but one you turn off and reboot, the original fault re-occurs. I'm the PC administrator and there is a single User login. There's a thread on the Windows help forum which suggests loads of solutions, but they all involve resetting permissions (and for me, they work only for the session; power off kills them). Here's the link.