It's unusual to have a problem with the shaft itself, but the cv joints in the shaft can go bad. If so, you will likely have a popping/clicking noise when you accelerate and/or when you turn sharply to the right or left. If the cv joints are really bad, you can crawl under the car, and try to shake the joints. A little play is normal, but a lot of slack in the joints is an indication that the joints are worn.
