Comment 9 for bug 309927

The fact that CapsLock didn't work suggests that this is a kernel issue. Since I'm not an expert on either, I will set the status to confirmed for xserver-xorg-video-intel (it will be set to invalid if it turns out to be a kernel issue) and open it for linux (the kernel) as well.

I will guess that this will be a difficult kernel bug, since it's so long between every time it occurs. The main thing that can lead the kernel guys to the cause is what the kernel dumps to the console when it crashes. This is hard to get - since you either need to configure an external console (see https://wiki.ubuntu.com/KernelTeam/Netconsole) or get a picture of the text console when the kernel has crashed. Since the crash usually happens when you're not working on the computer, maybe you can make it a habit to do a Ctrl+Alt+F1 to have the console up (Ctrl+Alt+F7 takes you back to the graphical interface). When it crashes you then take a photo of the monitor.

General information about kernel bug is available at https://wiki.ubuntu.com/KernelTeamBugPolicies . You can already include the Minimal information noted there (you already have the output of `lspci -vvvnn`).

PS: Anyone with more kernel knowledge than me, feel free to correct me if anything I wrote was inaccurate.