I have upgraded my Ubuntu 12.04 to 14.04 on my laptop recently. Everything on 12.04 worked perfectly, but now, when I choose to shutdown the laptop using either the GUI, or
sudo init 0 in the command line, it shuts down completely (screen and all LED's off, fans stopped, could hear hard drive shuts down), but then just powers up automatically again, and starts loading the OS. Using
sudo halt or
sudo shutdown -h now freezes on the splash screen.
I did install all the latest Ubuntu updates as of today. At first the wifi didn't work, which I fixed by installing the RT3290_u16 driver. I found that without this driver the PC shuts down and stays off, but then I have no wifi functionality. With the driver, the wifi works perfectly, but the laptop doesn't stays off.
I switched off any "Wake on LAN", "Wake on USB" and related options in the BIOS. I also modified the
/etc/default/grub file with the
acpi=force apm=power_off options. I also tried unplugging the AC charger just before shutting down.
I have tried scanning through the system logs, but to be honest, I don't really know what to look for.
The laptop with the problem is an HP ProBook 4540s.
Any suggestions would be appreciated.