So, we recently purchased a new Dell Vostro 470 with a Core i5 3450 processor and promptly installed Ubuntu 12.04 LTS, 64-bit on it. We've got two identical Dell displays connected to it and for the first couple days it ran beautifully.
Then it froze. After the first incident it pretty much happens every 2-4 hours or so when being used.
When frozen, the keyboard is completely unresponsive. The NUMLOCK key doesn't toggle the LED. No CTRL-SYSRQ-x key sequences (REISUB) work. CTRL-ALT-Fn sequences don't either, nor does CTRL-ALT-DEL. The mouse is likewise useless and the display is completely frozen with no screen updates -- not a single pixel ever changing.
We ran the full Dell Diagnostic suite that comes with the Dell BIOS which scans many hardware components, including doing their equivalent of a memory test (we did the "deep" or "detailed" version of their scan). No errors.
Then, while running Ubuntu I opened the Disk Manager and opened the Smart Data (or was it "Details") and had it do a surface scan (the most rigorous one) to check for bad sectors. No issues there.
We also ran cpuburn, one instance for each of the four cores for about a half hour with not even the slightest glitch. Just for kicks I even used debsums to ensure no package files were corrupted.
I also took a gander at the log files to see if anything stood out. Having viewed a lot of log files through the years, I didn't see anything that wasn't the ordinary, verbose chatter of the various systems. Also no core dumps or such that I can see either.
In short, the hardware and the installation seemed to be fine and the system and all peripheral hardware worked great -- right up until the whole system froze.
What I haven't tried yet:
I haven't tried pinging or ssh-ing into the machine when frozen. When I though of this earlier today, I decided I'd do it next time it froze. Now, of course, it refuses to freeze and just works normally. I'll do this when I can.
So anyone else with similar Dell hardware having a similar issue on 12.04? Since the hardware looks good, my last option in order to be able to send it back to Dell is if the problem exists under Windows too (since it's supported by Dell). I really don't want to have to restore windows and waste time trying to get it to freeze or blue screen, and there's a good chance it is some obscure driver issue.
So, if you have any diagnostic ideas or can report a similar problem, please let me know.