Has anyone come across this ?

I was at a friends place on the weekend and his laptop did this saying a temporary profile had been set up. He signed out, signed back in again but got the same problem. He logged in with safe mode, checked for any windows updates (there were a couple), rebooted and it was all ok again.

Now I've had it happen to one of my pc's.

Same thing, it appears to boot as normal, but after taking the password the little dots go around and it says 'Preparing Windows'. It takes ages to log in and I end up with the same dialog box with a desktop with no files on it. 

"We cant sign you into your account.

This problem can often be fixed by signing out of your account and then signing back in."

With the options to SIGN OUT or DISMISS.

I've tried everything I can find on the web. I've booted to safe mode, checked for updates (there were none), I've had another dialog box saying OneDrive needs an update but it downloads a version older than what I have already installed. I've checked for the ProfileList in regedit and it shows the old one and three new ones but none of the tips have made any difference.

I can see the old c:\users\my-pc folder with the files in it but its listed as c:\users\my

I've seen videos showing people deleting the .bak and renaming the other one but the comments have mixed results. I've copied the contents of the drive to a usb but I'd rather not have to reinstall everything if I can help it.

Any ideas on what I can try ?