I've tried pretty much everything that's been suggested. After I deleted HandsOff I got iTunes & System Preferences (so far) back again, but lots of other apps won't start up, so it's not all down to HandsOff.
So....ditto on crashes. How do I uninstall HandsOff? I suspect there's more to that than just deleting the app.
And if I may ask another question: I'm running TechTool Pro 7 right now to check files and such. TechTool is asking me for $40 to upgrade to 9. Is it worth it?
I would recommend caution running test & repair software that is out of date for your OS. I know there have been a couple of updates for TechTool Pro 9 specifically to support Sierra. TechTool Pro 7 will not have any updates for Sierra.