Ubuntu shuts down, but does not power off

I have an HP DV7 1140eb and have installed Ubuntu 9.04 32-bit (Jaunty)
When I try to shut down, I'm logged off but the my laptop does not power off. When i remove "splash" and "quiet" from the menu.list grub menu, I can see that it blocks on shutting down CPU0.

I have a workaround by powering off my computer via the shell with "sudo poweroff"

is acpi turned on?

acpi is turned off, should it be turned on?

i'm not at my laptop now, but i'll post my menu.lst tonight

yup, it should be turned on. Acpi sends a signal to the motherboard to shut off the computer completely.

Try to change menu.lst to inlude acpi=on or acpi=ht (most of the acpi services disabled)

computer halts with:

CPU1 attaching NULL sched-domain.
CPU0 attaching NULL sched-domain.

but doesn't power off

After rebooting the issue is solved, but I have to use the gnome panel Name > Shut Down to make it work. When I close the lid of my laptop, it remains in power on state.

Apparently I have to wait a couple of seconds before confirming the shutdown. I have to let the timer countdown for a couple of seconds.

I tried to disable the timer, but then the problem reoccurred. But now it works fine after waiting a couple of seconds.

Thanks for the help antikristian