Dear Capetonian
I don't know about your House but approx 10 Days ago (When the LGW TWR took a strike) I too had that very unpleasent feeling of "Oh bugger." caused by an ear splitting roar of thunder and the frazzeling sound of a lightening strike. togather followed by the smell of buring timber.
Not me this time (last Oct being the last hit) but the house opposite 30 Metres or so away. - House ariels always get it, however, I did not notice the effects that you describe: on my portable.
However prior to an actual Lighting discharge; a state of "Electrical Tension" or voltage gradient exsists between the cloud and the earth. The electrical field gradient may be so high; as to promote micro-discharges between you and the mouse pad.- hence if its a capacititive pad, things might go awary.
I did not mean Voltage field gradients were so high that "St Elmo's fire" is present (Time to unplug ! Quick), but a less energetic form of the phenomonon may be the cause. A warning to shut down from mother nature.
This is one for the PprUne "Sparks" to tangle with. -
CAT III