How to find the cause of a hang

Hi all,

I'm currently experiencing frequent (about once per week) hangs of a 
server that is about 1500 kilometers away from me. I have a serial 
cable on the box, and using minicom on the neighbor box I am now in the 
kernel debugger - but I'm at a complete loss as to what to do to figure 
out what is, in fact, wrong.

Calling panic or boot doesn't work - it just stops at "syncing 
disks..." and never actually reboots. I suspect something fishy going 
on with disk I/O, but I can't be certain of that.
The box responds to ping - until I call panic or boot - but no other 
services are working.

What can I do? I'm now at the db> prompt ... Help :)

/Eirik