12.04 hanging

[bikertappy]

Hi folks, I've recently bought a new PC and installed 12.04.
Every now and then it just completely hangs - the screen freezes, and sound that's playing starts looping or stuttering, and it's totally unresponsive to keyboard or mouse.

The only way I can bring it back is to force a power-down by holding the power button in.

Is there some other way to retrieve the system? Is there some way of getting a diagnostics dump so that I can try and identify the root cause?

I've tried dmesg but I'm afraid it doesn't mean much to me, and presumably this only records what happens from the time of the PC being booted up again, not the actual even that caused the crash?

I've used Xdiagnose and this tells me:
pci0000:00: ACPI_OSC request failed (AE_ERROR), returned control mask : 0x1d
[drmch_irq_handler] *ERROR* PCH poison interrupt.

Is this useful?

[rai4shu2]

I would suggest this (although it gets a little technical):

https://help.ubuntu.com/community/DebuggingSystemCrash

[bikertappy]

Right then. I've run memtest86 from the GRUB menu.
The first time I ran it, it actually ran for about 15 minutes and then got hung on some of the random number sequence tests.
Since then I've left it running overnight then checked it and it was fine with no errors.

[bikertappy]

The system continues to crash - I've visited the link rai4shu2 gave me, and have tried "Alt SysRq +1" and "Alt SysRq +t" and they do nothing - the system is totally unresponsive.

[bikertappy]

I've also looked at the /var/log/kern.log and I don't *think* the crashes are being caught by that.
I'm happy to post great swathes of it, but:
typically the log from the crashed session ends a few minutes before the crash (presumably the kernel isn't doing anything terribly exciting while I'm just surfing the 'net)
then the log re-starts with what looks like the system booting, lists a load of stuff about cleaning up orphans etc. so I don't *think* the crash is logged in it.
I don't really know what I'm looking at / for though.

[rai4shu2]

Right then. I've run memtest86 from the GRUB menu.
The first time I ran it, it actually ran for about 15 minutes and then got hung on some of the random number sequence tests.
Since then I've left it running overnight then checked it and it was fine with no errors.

Random failures are a sign of hardware problems. There's no point in looking for a software solution to a hardware problem. You can either seek hardware guidance or just put up with the hanging.

[wiggly81]

i have had a similar problem in the past and after much frustration i started removing / disabling hardware and in my case it turned out to be a 5 port usb 2.0 pci card. still to this day don't know why as the card was not even being used at the time but hey ho since removing it i have not had an issue.

[Sidney232]

I have had exactly the same problem and I'd like to run memtest86+ too. I'm having trouble finding out how to access the GRUB2 menu. Anyone know how to trigger this? I'm running a single install of 12.04 64-bit. I've tried changing a few of the settings in /etc/default/grub but nothing I change seems to trigger the GRUB2 menus on booting.

[bikertappy]

Update:
After passing memory tests, I figured maybe it was software and was *fairly* sure that the problems had only occurred when Firefox was running. So I looked at other browsers and found someone else that suggested Firefox made his install of 12.04 hang too. I'm now running Chrome and have had no further hangs. I'll reserve judgement for a while, but if it stays good I'll change the thread to solved. It may be a flash issue rather than Firefox itself, but I've got fingers crossed.

[bikertappy]

Sidney:
If you look in /etc/default/grub you'll see a reference to:
info -f grub -n 'Simple configuration'
Whack it into a terminal.
The problem I had with my fresh 12.04 was the GRUB_HIDDEN_TIMEOUT and GRUB_HIDDEN_QUIET_TIMEOUT
The info says that as default they're both unspecified, so I just deleted them. Hey presto - I now get a grub menu!
I guess the dev guys tried to hide it to avoid scaring people even less experienced than myself? Dunno - personally the more information I have the better. Note that's "information", not "data"
Anyways, that might give you grub, and might give you memtest, but see my previous post - my problem *may* have been Firefox related. I type this having had no hangs this evening, and 4 or 5 the previous 5 evenings so here's hoping...