Bug#271038: Work around
For debugging you could set BUSYBOX=yes and DELAY=5
in /etc/mkinitrd/mkinitrd.conf and rebuild the initrd.
At boot time you will be prompted to enter a tiny shell.
Using 'cat /proc/modules' in this shell session you
should verify that the driver for the root filesystem
has been loaded. If it is missing, then it should be
added to the modules file, too. You can even try to
manually mount the root filesystem and check the
error message. (Please umount it again before you
press the reset button. The tiny shell seems to be a
dead end street.)
Another reason for your problem might be that the
sequence of found disks has changed somehow for your
PC, e.g. /dev/sda has become /dev/sdb.