I've just become aware of an unpleasant side effect if you upgraded to Windows 10 then changed your mind and reverted back to Windows 7 or 8.1 (by the obvious router of choosing the 'Go back to previous build' option). If you run Task Scheduler then a huge slew of tasks show as corrupted (and so do not take place). In the long term this could compromise the security of your computer.
Fortunately a kindly soul has developed a fix which is here: https://repairtasks.codeplex.com/ . I've run this twice for two different computers that have gone back from 10 to 7. It worked in both cases (there were two stages to fix all the scheduled tasks).
