Well, I still don't know what the problem was, exactly, as I haven't heard anything more from the tech support people at the hosting company, but they apparently re-booted the database server around Noon today and the site seems to be running fine now.
In case you missed it, the site - and in particular, the message boards - were largely unavailable last night and this morning. There doesn't seem to be anything wrong with the scripts (nothing has been changed on the message boards for a while), but it was damned frustrating trying to get pages to load. Sometimes they would load, most of the time they wouldn't. I couldn't find any rhyme or reason for it, and - interestingly - the forum error log didn't turn up anything (at least, there was nothing unusual
Let's hope that doesn't happen again anytime soon.