I've been running a Dell Latitude D600 laptop on -current for a couple of months. After the last kernel update, I needed to switch to the non-SMP huge kernel due to lack of pae instructions.

Since then, I've seen 2 complete lockups. They've both happened when it was sitting idle, and in both cases, Xfce is gone, and the console is spewing kernel messages faster than I can possibly read. Something like:
I cannot find any hints in /var/log. Had to hold down power-button in both cases.

Any suggestions on what I might try to debug this further?

Open another virtual terminal if possible (Alt+F2 for instance) and try to identify the process involved with 'top'. And to look at the messages: 'tail -f /var/log/messages' which you can stop/restart with Xoff/Xon (that is to say, ctl+q/ctrl+s). Maybe the latter can work with the console #1 as well.

Happened again today. Alt-F2 doesn't work, ctrl-q/ctrl-s doesn't work. The spew looks like this:
Time doesn't change. I see the word "radeon" in the scrolling if I squint and stare.

Again, after reboot, nothing in /var/log/messages.

Any clue on what I can try for the next time?