It froze again.  I hit ctrl-alt-esc about N times before I got into the
debugger.  I viewed the process list, but couuldn't see anything odd
(I couldn't run any command like 'ls' because the shells no longer accepted
commands, so I don't know what state the 'ls' command would have been in).

Anyway, I typed 'tr' and here's what I got (didn't write down all the
addresses):

_Debugger
_sgetc
_pcvt_timeout
_softclock
_hardclock
_clockintr
_Xintr0
--- interrupt ---
_idle(f4c11194, f08d0a00, f0206ad4, 100, f4c12f40) at _idle+0xd
bpendtsleep(f4c11194, 128, f011b8a9, 0) at bpendtsleep
_sys_sigsuspend(f08d0a00, f4c12f88, f4c12f80, 0, 0) at _sys_sigsuspend+0x42
_syscall() at _syscall+0x21c
--- syscall (number 111) ---
0x40071bb9:
db>

Then I typed "continue" and the machine locked up so hard that I could
never get back to debugger - so I still don't have a core dump, argh.

I hope the trace above gives someone a clue of what's going on here..
Uptime was almost 24 hours when it froze.  I was just doing rm -rf in
a local directory, then changed the virtual screen in X11 and it froze
(I was able to move focus and use the remote machines, but nothing that
would require local disk access worked).

Sigh..

  -jm