Glad to see you swung by again!
A few things.
1. Do you have a vibration damper? Those are the little peices of plastic sometimes in the shape of a "W" or "P" that goes in your strings at the bottom fo the racquet. Just about everyone uses them as it keeps a lot of the vibration from going to your arm from the racquet.
2. Check to make sure one of your grommets is not loose. The groomet is the plastic peice that goes around the entire racquet and sticks through the holes that the string goes through of the racquet. They keep the string from pushing against the hard frame of the racquet. If one of those is loose and just disconnected from the racquet it would probably make that noise when you hit a ball. You can simple cut it off if it is disconnected.