Last week I replaced the internals of my desktop computer with a new ASUS P8H77-M PRO, Intel G2120 and 16 GB RAM. With one round of Memtest passed, I booted into my old Precise install and got bit hard by what appears to be Bug #993187: frequent hard lockups (multiple within a few hours of use). I installed linux-image-generic-lts-quantal (currently 22.214.171.124.29) and that seemed to resolve the lockups: I got more than two days of uptime (ending with an intended shutdown), half of which I was actively using the computer.
This morning, soon (half an hour?) after login, the kernel paniced with a reference to usb-storage (I’ll attach a picture). This was different from the lockups with the stock Precise (3.2) kernel: with them I never had any panics shown (only the frozen desktop) and the system had to be powered off to reboot, whereas with the panic here I could reboot using the chassis reset button.
There’s some USB activity in syslog just prior to the panic (Jan 7 at around 10:50), but I wasn’t using any USB devices at the time. I have used them with this kernel previously though, without issues, and currently am too (to transfer the panic picture from my phone). There’s a memory card reader/USB port panel (Akasa AK-ICR-17) permanently plugged into internal USB 2 and 3.
Sorry, the GM965 Express is the chipset, that one has a Mobile Intel GMA X3100 display adapter.
Confirming this on another G31 (MSI MS-7525). Haven’t seen similar on 5 other Precise setups I have, including laptops with Intel 855GM and GM965 Express on the graphics (the G31 has GMA 3100).
Bryce; no problem (and thanks for your working on this), for me the fbdev workaround is good enough to work and live with on this setup. If others affected by this feel differently, do take over with upstream.
Alright, I think this is safe to rule as invalid because the cause is most likely hardware failure: Oneiric boot media now also fails to boot here despite being the one used to install this system initially. I even went so far back as installing Jaunty (didn’t have anything more recent at hand, before Oneiric) and it also segfaults when X should start (though the graphical installer did work). I’ll still do tests if @Joseph disagrees (and has new ideas to test), but for now I’ll just settle for using fbdev (which seems to not trigger the issue).
I went back in Precise kernels  all the way back to 3.0.0-12.20. There seem to be no easy answers: now even 3.0.0-12.20 crashes with -intel.
I think this either means that the hardware’s broken, or that the issue has been lurking in kernels all the way back to (at least) 3.0.0-12.20, and was only triggered by some early Precise updates (during the time window I described above). As I said, it (definitely) wasn’t there when I filed Bug #903831 on 2011-12-13 (because I couldn’t have gotten far enough to trigger that bug with this on the way).
I’ll attach shots of current results with the early Precise kernels below just in case there’s anything useful there.
I think I’ll try ruling out hardware failure with Oneiric, either with the live disc (if that uses -intel) or by reinstalling.
*  https://launchpad.net/ubuntu/precise/+source/linux/
V3.3-rc6 still crashes, irregardless of RC6 being enabled/disabled.
With persistent booting I was able to get a panic  showing with 3.3.0-030300rc4, and it looks the same as what the dmesg I posted in #29  showed: print_bad_pte+0×187/0x1e0 is on top the Trace. Despite the numerous boots I was still unable to reproduce the initial printk+0x2d/0x2f, so it may be fixed in Main or masked by the print_bad_pte+0×187/0x1e0 (though this still is based only on two datapoints in a frustratingly random issue).
Whether RC6 is enabled or disabled doesn’t seem to have bearing on this. 3.2.0-17 produces printk+0x2d/0x2f either way , and 3.2.0-18.28 also panics, though less consistently: I was only able to produce a sure printk+0x2d/0x2f once , with 3.2.0-18.28 non-pae. Mostly the errors fail to reveal themselves, and when they do, they are different from printk+0x2d/0x2f but also from each other: a couple of times a warn_slowpath_common+0×72/0xa0 (as in Bug #917668, though the hardware and pointers are different) occurred , and once it was a Bad page map  in unity-greeter.
*  https://bugs.launchpad.net/ubuntu/+source/linux/+bug/926007/comments/32
*  https://bugs.launchpad.net/ubuntu/+source/linux/+bug/926007/comments/29
*  https://bugs.launchpad.net/ubuntu/+source/linux/+bug/926007/comments/33
*  https://bugs.launchpad.net/ubuntu/+source/linux/+bug/926007/comments/34
*  https://bugs.launchpad.net/ubuntu/+source/linux/+bug/926007/comments/35
*  https://bugs.launchpad.net/ubuntu/+source/linux/+bug/926007/comments/36
I’ll upload a bunch of new screenshots for reference. They’re all related to testing this so bear with me, I’ll explain them further after uploading.
I tested 3.3.0-030300rc4 and couldn’t verify that the panic that all the 3.2′s above have is still present. Unfortunately I couldn’t prove it doesn’t either: with -intel, the first boot resulted in the ’low graphics mode’ failsafe dialog with Traces in dmesg (I’m attaching it). All subsequent boots resulted in panics that didn’t reveal a Trace, so they may or may not have been the one at hand. The panics still occurred when LDM should’ve launched, visually it either just showed the last lines of boot log or that with the mouse cursor. (The what’s-that-key was also blinking on the keyboard.)