Humming water pipes

I have looked at many of the problems people have mentioned in their questions and I still need some help. My house is 5 years old and recently my water pipes have started humming when I turn on any cold water faucet in the house. The hot water does it occassionally too. When I turn off the water, the humming stops. So this seems to be just the opposite of what everyone else is having problems with. I have gone to the basement and held on tight to the cold water line and I feel the pipe vibrating. So I have two questions, first, do I have a problem that requires a plumber to fix and correct (I'm concerned about not ignoring a serious problem) or secondly, can I just put some straps around the water pipe by perhaps bracing a couple of 2x4's against it and then screwing down the straps tightly? Any help would be appreciated. Thanks a lot.