“Facebook Background Task Host” consuming 100% disk bandwidth
The program "Facebook Background Task Host" was consuming the entirety of my disk bandwidth on my Windows 8.1 computer. Further, there seemed to be almost nothing written about this program on the internet according to Google. Rebooting the computer didn't help: after the reboot it was there again. I did not remember downloading anything from Facebook to run on my computer.
The solution was to go to the Windows 8 start screen, and find the Facebook "app", and then uninstall it.