Hi raino.
I’ve had this after upgrading from windows 7. Disk activity 100%.
But to be honest, I don’t know what fixed it in the end. I was going back and forth between windows 7 and 10 several times, using rollback, reset, clean install. That was last August.
Now I’m quite happy with windows 10, even though my computer is not officially supported according to its manufacturer. (Acer laptop, 2011)
If you’re not in rush and have your windows 7 disk image, you may want to try to clean install windows 10 rather than trying to fix this. Starting with a clean system is a good idea anyway.
All sorts of things can go wrong during the upgrade.