Hurrah, I can post again.
I had become disgusted by the server upon which my site was hosted (to quote Red Dwarf, it was up and down more often than a kangaroo in mating season), so I asked my Webhosting provider to move it to a more stable one. It took nearly a week, but the new IP address seems to have propagated, and everything seems to be working well now.
During that week there were plenty of things I wanted to post, but naturally I can't think of anything now.