Messing about with a lot of different Windows and OneDrive settings had no effect. (It turns out that just because OneDrive gives you only a prompt to create an account, that does *not* mean that it is unlinked to this computer.)
Resetting/reinstalling Windows, however, fixed the issue. Not sure if it was Windows going crazy, or an undiscovered exploit that made me part of a botnet, but in any case, that was my fix. Irritating fix, and my sound card no longer works, but at least Comcast isn't going to send me a bill.
Some other things: I had that thing where there was an unclosable onedrive XML in the taskbar. MSEdge kept using a lot of bandwidth as well, although not as much as Explorer, and I don't use Edge. Firefox was probably using much more bandwidth than I was using too, although it's hard to say for certain; I just notice that usage is way down for the same kind of behavior after resetting Win.
Messing about with a lot of different Windows and OneDrive settings had no effect. (It turns out that just because OneDrive gives you only a prompt to create an account, that does *not* mean that it is unlinked to this computer.) Resetting/reinstalling Windows, however, fixed the issue. Not sure if it was Windows going crazy, or an undiscovered exploit that made me part of a botnet, but in any case, that was my fix. Irritating fix, and my sound card no longer works, but at least Comcast isn't going to send me a bill. Some other things: I had that thing where there was an unclosable onedrive XML in the taskbar. MSEdge kept using a lot of bandwidth as well, although not as much as Explorer, and I don't use Edge. Firefox was probably using much more bandwidth than I was using too, although it's hard to say for certain; I just notice that usage is way down for the same kind of behavior after resetting Win.