Keys are stuck in game.

Upon playing the game, I experience the keys to randomly get 'stuck'. Not literally, my keyboard is fine, I've checked. It's when in game I move forward constantly without stopping after pressing 'W' once. Like the space key, this results in constant jumping. It happens on every map, survival and creative and has been this way since I downloaded it. I have tried deleting and downloading it again several times. I spent an evening with your tech support on minecrafthelp and they checked my launcher log and game output and they were not able to diagnose an issue.
I love minecraft and would love to play the game I bought. Please help

Terry Silver
Username: infinitymoose