Kernel panic after upgrade

[Mark Halegua]

I upgraded from 8.04 to 9.04 using the alternate CDROM method and the system
now kernel panics.

Here are the lines I get before the panic.

Starting ...

[ 1.919656] ACPI Invalid _PSD data
[ 2.024321] Kernel panic - not syncing VFS: Unable to mount root fs on 
unknown - block(0,0)

Never had to troubleshoot a kernel panic before.  Is this having trouble with 
grub, or is the menu.lst entry incorrect in some way?  The partition the root 
directory (and the subdirectory /boot) in hda5 and the root entry for the 
vmlinux kernel in the menu.lst is (hd0,4)

If I'm understanding this correctly (not sure that I am), it's not getting the 
proper root and not getting the proper boot.

If that's true, how do I fix it?  I can access the filesystem and the 
partition and can edit any text configuration files.

Any help is appreciated.

Mark