100% disk usage. CPU 7%; Memory 62% (firefox); Network 0%. Used space: 1.48 TB; Free Space: 333 GB (1.81 TB capacity). File System: NTFS. 64-bit Operating System; 8GB RAM. i7-3770 CPU @ 3.40 GHz, Windows 10.

 I can't bring down the disk usage. I've disabled Superfetch, BITS and the Windows Search Service. I uninstalled Viber and Skype.  I stopped Windows from using my PC to share/deliver updates. I updated my BIOS. I ran a system assessment (F12) The Disk usage doesn't seem to change from 97-100% usage. I'm at a complete loss.  Any ideas?

Plus, I have this weird Ethernet usage that I can't explain: