I had an old keyboard which had this problem and I bought a Deathstalker Chroma to see if it fixed it, but I still have the same problem.
When playing a game, when I sprint I normally hold shift to run on Skyrim, however only recently it has been acting up. I would have to tap shift twice and then only hold W to sprint forward and to stop I need to press it again.
When I only press it once it thinks i'm still pressing it, its the same idea for my control key.
Please help me as I have no idea whats going on!