The User Profile Service service failed the sign-in...

...User profile cannot be loaded.

I am using a dual-boot system with Windows 10 & Ubuntu. And I have for sometime now without a problem.
Maybe the newest thing I installed has something to do with this (?). It was Ext2Fsd
This morning I switched to Win10. Using Grub2, I believe I chose Windows UEFI bkpbootmgfw.efi.
Only to find this message as a result of trying to login with my usual PIN #. Then I switched to use my password, and it worked. However, everything continued loading very, very slow. Slower than usual that's for sure. Once it seemed stable, I noticed the Windows key was not available. Also Ext2fsd had not loaded on its own, so I manually made it run. I logged off, but this time even with my password it would not log me in. I rebooted, but this time I chose Windows Boot Manager (UEFI on /dev/sda7) (I think).
Windows started doing some fixings, and said it would be over an hour. It really only was a few minutes, but I was not there when it was done. It rebooted on its own, but it went to Ubuntu as it is the 1st on the Grub2 list. I wasn't able to continue checking on this as I had to go to work.

Other people have advised to gain access to another Win10 installation (on PC or a USB drive), to copy the c:/Users folder and replace the one in your pc.

What do you guys think?

Thanks in advance,

DPC