I'm running a clean install of 12.04.02 (i.e., direct from the 12.04.02 install disk, not upgraded from 12.04.01). All packages are up to date. My hardware includes a Gigabyte GA-Z77-HD3 with a Sandy Bridge Celeron, and I'm using the on-board Intel HD graphics.

I keep getting GPU lockups. They're not the "false" ones often reported. The error message (copied by hand because Apport won't let me copy from the UI) is:

[sandybridge-gt1] GPU lockup IPEHR: 0x23002000 IPEHR: 0x0b140001
Under "package", it says "xserver-xorg-video-intel (not installed)". Further down, it tells me to upgrade or install that package. But when I try to do so, I get this error:

kevin@aphrodite:~$ sudo apt-get install xserver-xorg-video-intel
[sudo] password for kevin: 
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 xserver-xorg-video-intel : Depends: xorg-video-abi-11
                            Depends: xserver-xorg-core (>= 2:
E: Unable to correct problems, you have held broken packages.
I don't understand what that means, or why I'm getting a crash report from a package that isn't even installed. What should I do next?