How to diagnose lockup?

[Denis Hennessy <dhennessy network365 com>]

On my test machine (dual-athlon), fresh install of beta 2 with all 
updates applied (-411 kernel), I'm getting frequent lockups which I've 
just figured out how to make happen on demand. The problem is: the 
machine needs a power cycle once it happens and there's no log files, or 
core dumps to diagnose the problem. I'd like to have a bit more 
information before filing a bug report.

To make it happen, I start mozilla and type anything into the web 
address field. Within a few characters the machine will lock hard with 
no mouse, keyboard or network response. I have to power it off to recover.

What should I do?

/dh