HP Pavilion hangs on shutdown

[Pascal Pein]

A HP Pavilion laptop with the latest 14.04.2 LTS updates does not shut down properly.

Instead of shutting down normally, the system keeps hanging with a black screen and the fan running until the laptop is switched off manually with the power button.

Setting "acpi=off" in the boot options resolves the shutdown issues.

Setting "acpi=ht" as boot option causes the shutdown to hang.

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: linux-image-3.16.0-38-generic 3.16.0-38.52~14.04.1
ProcVersionSignature: Ubuntu 3.16.0-38.52~14.04.1-generic 3.16.7-ckt10
Uname: Linux 3.16.0-38-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.11
Architecture: amd64
CurrentDesktop: Unity
Date: Mon May 25 15:41:19 2015
InstallationDate: Installed on 2015-05-14 (10 days ago)
InstallationMedia: Ubuntu 14.04.2 LTS "Trusty Tahr" - Release amd64 (20150218.1)
SourcePackage: linux-lts-utopic
UpgradeStatus: No upgrade log present (probably fresh install)

[penalvch (penalvch)]

Pascal Pein, thank you for reporting this and helping make Ubuntu better. Please execute the following command, as it will automatically gather debugging information, in a terminal:
apport-collect 1458590

[Launchpad Janitor (janitor)]

[Expired for linux (Ubuntu) because there has been no activity for 60 days.]