Error rebooting after upgrade from 2.6.12-i36 to 2.6.15-i686

[Arnau <arnaulist@andromeiberica.com>]

Hi all,

  I've installed a new Dell poweredge 850 server with SCSCI disks
formated as ext3 from a netinstall, it run smoothly and installed the
2.6.12-i386 kernel image. After the aptitude dist-upgrade, I upgraded
the linux-image to the 2.6.15-686 and also to 2.6.15-686-smp (having
with both the same result) and when I reboot the machine it displays the
following errors:

  Alert! /dev/sda1 does not exist. Dropping to a shell!

  /bin/sh: can't access tty; job control turned off

and a busybox shell appears. Anybody knows how to fix this?

Regards
--
Arnau