Udev problem when rebooting....no filesystem found

["miguel velasco" <miguel.suscripcion@gmail.com>]

Hi all! yesterday night I installed my Debian Etch widh KDE 3.5 at
home and everything could be ok untill I rebooted my computer. At this
moment in the boot process watched:

Waiting for root file system...... (hay se queda unos minutos)
Aler! /dev/hda3 does not exist. Dropping to a shell !

Now I have limited console with no all commands and the next file
system in my PC:
$ df -h
filesystem    Size      Used    Available    Use % Monted on
udev            379.0M  28.0K   378.9M      0%        /dev

During the installation of th KDE 3.5 one packet named Udev was kept
back and it didn´t upgrade....I thought it was no important and now I
suppose it was.
The questions are: what is udev?  why my file system is /dev?  where
is /dev/hda3?

Thanks very much for ur time.
--
MIGUEL