Have you ever had such a problem?
# reboot bash: /sbin/reboot: Input/output error # shutdown -r now bash: /sbin/shutdown: Input/output error
Obviously, there is a problem with your drive. These commands are failing because the kernel is unable to load the /sbin/reboot and /sbin/shutdown binaries from the disk so that it can execute them.
At least you could try this
echo 1 > /proc/sys/kernel/sysrq
and then talk direct to the kernel
echo b > /proc/sysrq-trigger