So, to put this all in one post, rather than having you read all of the tweets: I got a new external hard drive the other day, and plugged it into my Windows 10 desktop. I copied almost everything over (with the exception of a few folders I don't think need to be backed up) from my old drive to my new drive. I then switched their drive letters (so the new drive is now set to the same drive letter the old drive used to use, and the old drive has a new drive letter). Then, I set up SyncBack to keep my new drive backed up on my old drive regularly. Having both of those drives plugged in at the same time, presumably because there's some sort of system file stored somewhere on them that's getting duplicated or that Windows is finding in the wrong place, caused it to completely geek out and basically stop working. Unplugged the old drive, and things *seem* to be back to normal again.
Ultimately, though, it would be nice if I could figure out what the heck was causing the issue, so that I could set things up again to backup to the old drive (at least until that drive dies). ‎- Mr. Noodle
I do still have my files all backing up to another, network-attached drive as well, so the old external drive is basically just a backup of a backup, but it'd still be handy to have ‎- Mr. Noodle
Do you use BitLocker at all? ‎- Jennifer D.
I do use BitLocker on one of my partitions, but that partition isn't on either of these external drives. ‎- Mr. Noodle
Update: Things were still screwed up, so I ended up having to reset the computer to the original Windows 10 install. One lesson I learned in resetting everything: I really should have exported my SyncBack backup profiles before resetting things. ‎- Mr. Noodle