I updated the kernel of my gateway tonight : small machine with no screen, no keyboard, only a network connection. Upon updating I rebooted and heard its ``beep''... Yep, The kernel refused to boot.
One screen and one keyboard moving and plugging later, the message was : "No setup signature found".

A bit of googling later, I found the problem:
- http://kerneltrap.org/mailarchive/linux-kernel/2007/8/2/154556
- http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=451701 (yep, I enriched the bugreport)

Cause: very old grub does not like very recent kernel. Solution: update grub stage files in /boot/grub/ through grub-install.

Thus another remote-reboot-with-a-new-kernel-I-just-installed-like-a-real-man failure. Better go to sleep, now.