During general use my laptop (Lenovo Thinkpad Edge 15 running Ubuntu 12.10) will suddenly mute its volume and stall for a few seconds, seemingly for no reason. At the same time if I'm in a terminal the previous command is selected.

I have observed that the problem seems to occur if my wrists are resting on the laptop below the keyboard, to either side of the touchpad, but not if they're held above it. It has also seemed linked to using the nub mouse or the nub mouse scroll button (located between the left and right clickers directly below the space bar). Disabling the track pad has not helped the issue, though I have not tested disabling the nub mouse or associated buttons.

I installed a keylogger to help monitor and then used the system for a while, sure enough it happened a few times and I isolated the following series of keypresses that occur of their own accord:

<Up><E-71><LAlt><#+1>j<#+61>

The <# items seem to be a count, which is strange as the Lalt key would not normally record a count and I've not been able to press any combination which causes this in normal use. The number after the j seems arbitrary, from 1 up to hundreds. The E-71 key is the laptop's volume mute, on the F1 key (the F keys have a separate Fn trigger button).

At times the volume has switched on and off, I suspect with this process happening multiple times. I recreated it a single time by pressing hard on the laptop case to the left of the trackpad, but have not been able to do this again. So there may be a hardware element, though the laptop is otherwise in good working order and physical condition - it has never been dropped or suffered an impact, and this problem has only been occurring for a few weeks, without anything that comes to mind as a trigger for when it started.

It may be just a hardware problem, but if there are ways of working round it (the small stall is likely due to the weird key combination confusing the OS) I'd be interested, and more so if anyone else has experienced similar.