Ubuntu won't turn off computer after shutting down

[Hekabe]

Ubuntu doesn't turn off my computer after it shuts down. All the normal shutdown dialogs come up and then the screen goes black, but it stays powered on.
I have a Dell Latitude D630. I use it with a dock most of the time, but I tried it off the dock and got the same result.
Any help?

[angry_johnnie]

Not entirely sure this will work with grub2 but worth a try:

press alt + f2 and type

gksu gedit /etc/default/grub

it will open a text file.

look for GRUB_CMDLINE_LINUX_DEFAULT=" "

after the = sign it may say something like "quiet splash"

add "acpi=force" minus the quotes

so it should be something like this:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi=force"

Save and close the file.

Then open a terminal and type:

sudo update-grub

Press enter and type in your password.

Reboot, and try to shut down.

I had to do that with an older computer I had, but that was with ubuntu 7.04 and legacy grub. It may still work, though.

[Hekabe]

That worked. Thanks a lot.