Kernel panic after FC2->FC5

[Jack Howarth]

    Today we tried updating an i386 Fedora Core 2
workstation to Fedora Core 5. The upgrade install
completed without complaint until we rebooted the
machine. At that point I got a kernel panic with
the message...

Kernel panic - not syncing: Attempted to kill init.

...after the line stating that the kernel is being 
uncompressed and booted. What is the best approach
to debugging this and is there specific set of
causes for this problem?
            Jack