Comment 224 for bug 600453

changing to GRUB_CMDLINE_LINUX_DEFAULT="quiet acpi_osi=Linux" did the job for me.

 I'm running Ubuntu 11.10 amd64 on an HP 2540p EliteBook.

$ sudo lspci -v -s 00:02.0
00:02.0 VGA compatible controller: Intel Corporation Core Processor Integrated Graphics Controller (rev 02) (prog-if 00 [VGA controller])
        Subsystem: Hewlett-Packard Company Device 7008
        Flags: bus master, fast devsel, latency 0, IRQ 45
        Memory at d0000000 (64-bit, non-prefetchable) [size=4M]
        Memory at c0000000 (64-bit, prefetchable) [size=256M]
        I/O ports at 5058 [size=8]
        Expansion ROM at <unassigned> [disabled]
        Capabilities: [90] MSI: Enable+ Count=1/1 Maskable- 64bit-
        Capabilities: [d0] Power Management version 2
        Capabilities: [a4] PCI Advanced Features
        Kernel driver in use: i915
        Kernel modules: i915