So, I fixed the disk space issue over on
Spaceling Cafe, only to discover that that was the least of my problems. I still can't update the blog because my previously perfectly functional MovableType templates are full of errors. I think my Movable Type installation may have been upgraded recently - my hosting provider does that for me occasionally, but this is the first time it's ever seriously broken anything.
It looks like the quickest fix might be to just rip out all of the code related to displaying comments, which would be inelegant. Or to grab some premade templates from somewhere. But I've had enough of dealing with it today.