I had this same problem when I updated my kernel from 2.4.25 to 2.6.7. The way I got around it was to disable the acpi module (advanced power management). For grub, write something like this:
title Debian GNU/Linux, kernel 2.6.7-1-686
kernel /boot/vmlinuz-2.6.7-1-686 root=/dev/hda1 acpi=off
And then try it again. Hopefully it will work for you then. Although I'm a little disappointed that I have to disable power management.
If anyone has an idea of how to fix the problem without disableing acpi please share.