Ok, I just happened upon a segmentation fault. Actually, a plethora of them. I get a few on boot (like when loading sysklogd), and on shutdown.

Here's the series of events:

1) Installed another stick of RAM (already have a 512 meg stick, DDR266, stuck in a 256 meg one of the same brand and speed). BIOS set it to dual channel automatically.
2) Upgraded ALSA to 1.0.7.
3) Installed Rosegarden, and used sfxload to load soundfonts
4) Installed Ardour (through a slack pkg)
5) tried to run ardour, but forgot to get the deps for it.
6) Tried to run firefox, got segmentation fault.
7) Tried to run pkgtool, and it just said "package removed successfully" whenever I went to the remove package option.

I rebooted, and it wouldn't get past loading hotplug. I rebooted again, and it managed to let me log in. I started X, and tried to do basic stuff. ls doesn't work - segmentation fault

I think it might be the RAM, so I'm running memtest86 from a bootable CD. It's been through 2 sets of tests, and nothing cropped up. I'm going to pull the extra stick and see what happens.

.. And that doesn't fix it. So, looks like I'll be wiping and reloading - however, I'd like to determine what caused it. I can't wipe and reload yet - my slackware CDs are on campus, and I don't get back until Sunday.

*edit* btw, I'm running Slackware 10.