System hangs while rebooting on Debian

I have Debian (Kernel 2.6.26-2-686) installed on two computers. On one of them it reboots quite finely but I am having following problem with rebooting Debian on my second computer.

When i type reboot at the Linux prompt, following messages appear and system hangs up after saying "Restarting System":

Broadcast message from root@myname (tty1) (Sun Jan 17 11:23:26 2010)

The system is going down for reboot NOW!
INIT: Switching to runlevel: 6
INIT: Sending processes the TERM signal
Saving system clock
Stopping enhanced syslog: rsyslogd.
Asking all remaining processes to terminate...done.
Deconfiguring network interfaces...done.
Cleaning up ifupdown....
Deactivating swap...done.
[ 31.789103] Restarting System.
_

Normally when the sytem is busy _ sign blinks but _ at the last line above does not blink which shows, the system hanged up. I tried all keys but the screen is still frozen at the same point.

The difference that I noted between my two computers is that I don't have ACPI support in the BIOS of the system which is giving me this error whereas the BIOS of my first computer do have ACPI support on which Debain do not give this restart-hanging problem.

I have also disabled running the acpid script by running

update-rc.d -f acpid remove

but the problem still persists on the second computer.

Any ideas to solve or get around this problem?

Update:

The computer on which I am facing this problem is DELL Optiplex 330 (2.8 GHz, 1 GB RAM)

for debian squeeze amd64 on Dell latidute 390MT, with sandy bridge use reboot=pci

in details :

$>sudo nano /etc/default/grub change the : GRUB_CMDLINE_LINUX_DEFAULT="quiet" to : GRUB_CMDLINE_LINUX_DEFAULT="reboot=pci quiet"

(cltr+0, cltr+x)

$>sudo update-grub

reboot now works perfect/

Thanks for all those who helped. :)

I tried passing "reboot=bios" as kernel option. This solved the reboot hanging problem. My system is no more hanging now.

Read this for details on passing kernel options and seeing alternative values that may solve your problem.

For some systems, such as the Dell T1600, reboot and acpi kernel options may not be effective, but one person was able to solve this same problem based on a recommendation to disable a BIOS feature:

"VT for Direct I/O"

One may also be able to upgrade the BIOS to enable reboot, but this is untested.