I spent the last five days updating the software that runs this site. It was a pretty nightmarish process. First the update changed every URL on the site. Once I managed to fix that, I discovered that the server was repeatedly crashing.
My webhost looked into the issue and found that spammers were trying to submit large amounts of comment spam, which was locking up the servers. (Most of the spam wasn't making it onto the site because the spammers apparently weren't filling out the captcha form, but I guess it was still putting a strain on the server to have to keep denying the spam.) So to combat this, I had to make one large change to how the site runs. From now on, only registered members can submit comments. In fact, only registered members will even be able to see the comment submission form.
Of course, this won't stop spammers from registering and posting spam. But it will stop the lazier type of spammers who simply direct their autobots at the site's comment form and blast away until the server collapses.
This change will mean that there will be far fewer comments on the site. And I know that some people are basically allergic to having to register for sites. But the spammers didn't leave me much choice. And it should make the site more spam free and thus more pleasant for people who do leave comments.
So the spam problem was addressed, but the servers were still freezing up. After a lot more investigation, one of the guys from the software company traced the problem to a bug with how the software was dealing with comment pagination, and he fixed the bug. So, at last, the site appears to be working. Fingers crossed.
I'll keep an eye on the comment pagination problem, and if it looks like it's not fully resolved, I'll simply turn off pagination for all threads and set the comment count high enough so that all the comments for most threads can fit on one page. For those few threads with a lot of comments, I'll ask people to continue the discussion over at the forum, because the forum's software doesn't seem to have the same problem with pagination.