Kernel panic with linux-headers-3.2.0-0.bpo.2-amd64

[Nick White <nick.white@durham.ac.uk>]

I had been running linux-headers-3.2.0-0.bpo.1-amd64 for the last
week without problems. Last night I upgraded to
linux-headers-3.2.0-0.bpo.2-amd64, and was sad to find this morning
that it panics early into the boot (I believe when loading the
kernel, not the initramfs).

I'm not sure how to debug this; the panic output on the screen is
far from complete (as it hasn't got around to setting a nice screen
mode by the time it fails), and I don't have a way of capturing it.
Does a panic write something somewhere? Can I encourage it to do so?

Any help tracking this down would be much appreciated.

A related question (I'm new to Debian) - why does
apt-get dist-upgrade remove my previous kernel when upgrading? It
caused considerably more annoyance to get my box back up when I
found the new kernel wasn't co-operative.

Many thanks,

Nick