Due to some unexpected issues in Win 10, I rolled back to Win 7. It was very quick and apparently easy. HOWEVER, I found none of the scheduled tasks I had created worked. Opening Task Scheduler presented me a succession of 62 error messages (eventually I counted them!) indicating my own tasks, and many others created by other applications, including Microsoft itself, were corrupt. Fortunately, for me, I was able to recover everything by restoring from a partition backup, and all is now well. But beware of rollback if you don't have a good backup or a System Image.

There is a technet forum thread relating to this issue: