If you choose shutdown instead of reboot, does the computer shutdown properly?
Is this a desktop or laptop? Can you post the specs? including the motherboard chipset?
Shutdown / reboot problems are often related to acpi configuration issues. When you boot the computer, hit F6 to add boot options. Type acpi=off and boot up. Then try and reboot and see if it reboots ok. If it does, then that confirms that is an acpi problem. You could then try booting with acpi=force and see if you can still reboot properly.
Last edited by tommcd; 05-24-2009 at 01:30 AM.