Comment 5 for bug 1002670

Thanks, I hadn't marked it as Invalid as I'm still investigating. In my opinion we have to keep an eye on this issue, maybe it is a combination of hardware failure with bad reaction of the Linux kernel. Surprisingly I left the system running for a while and suddenly "dmesg" stopped reporting the error and the system came back to normal. I have rebooted a couple of times afterwards with no problems so far (of course it may fail any time now).

So far the comment that makes most sense to me is:

https://bugs.launchpad.net/ubuntu/+source/linux/+bug/550559/comments/102

All disk checks, except for the Dell diagnostics that I mentioned in my previous comment, report that the disk is perfectly fine, no errors found, so this does not seem to be a purely hardware-related problem.