Why do I get a reboot instead of a shutdown?

Solution 1:

I had the same issue with new acer aspre v5 notebook. It has been solved by enabling laptop-mode as running

sudo apt-get install laptop-mode-tools

I faced the same issue after I installed Ubuntu 12.04 on a newly built machine. This answer on another post helped me resolve it:

I resolved by adding acpi=noirq to the kernel arguments

sudo editor /etc/default/grub

Add

GRUB_CMDLINE_LINUX_DEFAULT="acpi=noirq quiet splash"

Then

sudo update-grub