I recently updated my debian box and then upgraded. Everything was fine untill I rebooted. Once I had rebooted the boot process would hang up @ some place but somewhere during this process I would get "waiting for root" to mount. I had no idea what that meant and I was going mad.
I did a lot of searching and then I came across a web page that said something on these lines:
– boot your box with a Debian bootable CD
assuming your / is on /dev/hda1 execute the following commands in a shell (ash or whatever is the default shell)
mount /dev/hda1 /mnt/debian
apt-get install udev
something went wrong during the upgrade process and udev had troubles. This should fix the problems.