I had a problem with a break locking and some noise. I actually found that the break fluid had either been replaced with water or had deteriorated. I flushed the system with air and replaced the fluid (this is teadious) and it seems to have gotten a bit better.
CHeck your fluid to see if it rust colored or anything but clear, If it is you need to do the same. You can also buy some silencer gel or clean the dust off the callipers.