Linux freeze at reboot

Problem:  My Linux environment (Oracle Linux 5 update 7 on Dell T1600) goes through the entire shutdown sequence normally, then hangs on a blank screen at the point when it would normally reboot the computer. It has to be manually power down and restart

Solution: Add "reboot=b" to kernel parameter (for Grub, it is inside /boot/grub/grub.conf)

For 64-bit OS, you may need "reboot=p,e,f"

Here is a excellent link about this topic

http://linux.koolsolutions.com/2009/08/04/howto-fix-linux-hangfreeze-during-reboots-and-restarts/

Update (July 3, 2012) : The following also fix the problem:

"VT for Direct I/O" from the bios