I've never seen a motherboard cause specific keys on a keyboard to fail before, so I doubt very much if there is a problem there. It is surprisingly common for keyboards on laptops to fail (I have 2 here at this moment with non-responding keyboards), however it is not very easy for an inexperienced person to replace one, as some laptop facias are quite complex to remove without causing damage. I would suggest taking it to a shop for a replacement keyboard, if you decide you can't live with lugging a USB replacement around with you.
Good Luck