one thing i would suggest, fresh install win 10 once you ready to upgrade as you can use your win 7 key. It would avoid bringing any left over nasties along for ride.
system restore can be more trouble than its worth
it sounds like something is still on your system
I guess it might be some sort of registry bug but no rootkits are coming up so I'm not sure what it would be...reeeeaaaallly trying to avoid doing a clean install of Windows 10, though.