I was called in to fix a friend's malfunctioning HP Pavilion. She's not sure exactly which model, but the sticker on the bottom says "G60".

The problem was a failed upgrade to 12.04. I was able to mostly repair it with sudo apt-get -f install, which ran setup and configuration for several hundred packages.

The biggest problem at the moment is Xorg. The login screen (lightdm) loads normally but at a reduced resolution (1024x768 instead of 1366x768). But once you log in, it looks like this:

Observe that the colors of the dock on the left and the bar at the top are normal. But the background is filled with bizarro color-skewed ghost images of the desktop. In all cases, the actual contents of any programs you run is a totally illegible mess, except that the bar at the top of any program windows looks and acts normally.

And the ghost images are interactive! For example, if you click the icon in the top right corner to get the "shut down" menu, the same menu will appear in the ghost images below. Starting a terminal will start a terminal window in both the real desktop and the ghost images, and moving it around updates both the real and ghost desktops.

I suspect Xorg is using some kind of wrong driver and/or parameter for the graphics hardware. Here is the graphics-relevant portion of the lspci -v output:

00:00.0 Host bridge: Intel Corporation Mobile 4 Series Chipset Memory Controller Hub (rev 09)
    Subsystem: Hewlett-Packard Company Device 360b
    Flags: bus master, fast devsel, latency 0
    Capabilities: [e0] Vendor Specific Information: Len=0a <?>
    Kernel driver in use: agpgart-intel

00:02.0 VGA compatible controller: Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller (rev 09) (prog-if 00 [VGA controller])
    Subsystem: Hewlett-Packard Company Device 360b
    Flags: bus master, fast devsel, latency 0, IRQ 44
    Memory at d0000000 (64-bit, non-prefetchable) [size=4M]
    Memory at c0000000 (64-bit, prefetchable) [size=256M]
    I/O ports at 5110 [size=8]
    Expansion ROM at <unassigned> [disabled]
    Capabilities: [90] MSI: Enable+ Count=1/1 Maskable- 64bit-
    Capabilities: [d0] Power Management version 3
    Kernel driver in use: i915
    Kernel modules: i915

00:02.1 Display controller: Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller (rev 09)
    Subsystem: Hewlett-Packard Company Device 360b
    Flags: bus master, fast devsel, latency 0
    Memory at d2500000 (64-bit, non-prefetchable) [size=1M]
    Capabilities: [d0] Power Management version 3

I'm not sure what to check next. I would ordinarily check xorg.conf to see what it says, but that apparently doesn't exist any more, and my googling has not yielded any useful techniques for getting Xorg to tell me what settings it decided to use.

The weird part is that it works fine on the login screen. It's only when you actually log in as a user that the display gets screwed up.

Suggestions?