We recently replaced the valve in our bathtub/shower as hot water would not go to the shower faucet. Now every time the washing machine fills (located downstairs other side of house), the pipes bang very loudly in the bathroom where the valve was fixed. Does this mean the valve is faulty or needs to be replaced again?
Pipes normally bang because they are banging against something. Try securing them.
Your problem made me curious, so I did a little research and found something that I hope will help you out: http://www.dummies.com/how-to/content/how-to-quiet-noisy-water-pipes.html. Good luck.