We had a professional install 2 Hampton Bay 52"flush mount celing fans, (Bay Island is also listed on the box) Model 104-478. The motor buzzes in both celing fans, which drives me crazy.
I took one back, got another, and it's buzzing too. It's getting frustrating to take the motor down, and not an easy task. All this happened yesterday. We did install one in another room at the same time that works great, no buzzing. Should we try another, get a different fan, or is there something we can do since this one is already installed.

Try without the light kit/glass to eleminate as a possibility.

Check to see if the motor has the ability to be "oiled". If so, then you might try doing that.

You could also try hooking up the electric motor on the ground without the blades (i.e. not hanging it up in the ceiling) to see if the motor is making noise, but you would have to be very careful, and know how to hook up wires, have a long piece of romex, etc. Hope this helps you out.

The oiling idea doesn't apply. Running it without the blades is a good idea, to see if the noise persists.

Either something is loose (screws, etc) or it was installed without vibration isolating material.

General ceiling fan troubleshooting and help FAQ- Ceiling Fans N More (http://www.ceiling-fans-n-more.com/ceiling-fan-general-troubleshooting-and-FAQ.php)