The error you see is-

        Stopping identd services: user_memory_flush_task: 
        memory not in hash table
        Kernel panic: user_memory_delete: fatal bug

This is a very old bug, and has been fixed for several months, 
but the kernels on ftp.mklinux.org in the pre-R1 area are also
very old.  

Please grab

ftp://ftp.mklinux.org/pub/contrib/vmlinux.000203.gz

and use that instead of the vmlinux that's currently in your
/mach_servers directory.  The problem will go away after the
next reboot.

If you still have the old kernel and need to shutdown you can
kill identd -before- running the shutdown command.