I recently bought a refurbished laptop that originally had windows 7 in it but i upgraded it to windows 8.1. For some reason some of the keys don't work properly sometimes(L, O, and 9). All the other keys work fine. Just seems like those three are the problem. I checked the keyboard drivers and they seem ok. Could it still be the drivers or is it the specific keys?
refurbished products are the products which has been used by someone and been replaced due to a defect which the company later fix and sell for a low price than usual so if its not dust may be something else so its best to use your warranty.