Well, that was (and remains) annoying.
After more trying to find packages to sort out dependency issues, things were about as in the last post: not working. Removing xchat and reinstalling from the Mandrake install CDs also didn't quite work.
With masem's help some debugging went on and after considerable time I have xchat 2.4.5 back, compiled rather than an rpm install. That's the good. The bad is that the crash-on-DCC after (not all that an) extended uptime is still there.
There might be a bit more to this, though. Every once in a while I thought I saw a flicker on the screen. This doesn't happen too often, maybe once every few days. But I just saw it all too clearly as I was typing this entry. I saw what seemed to be an LJ icon (or maybe a Nautilus preview icon) fly across the screen at an angle (not perfectly horizontal). It started well outside the browser window, too. I don't know what it is, but it's Not Good.
That only gives me more reason to consider a fresh install of some distribution. I've decided it will happen, but I haven't settled on which distribution just yet.