As soon as I started storing music on my timecapsule and streaming through itunes to airport express, the stream would stop after a couple songs. When playing music on my hard drive there was no problem, just when streaming from the remote hard drive. After searching and experimenting I found no solutions. I downloaded a free trial of Airfoil and realized that the stream was uninterrupted whether from the TC or local.
I know it's not a free solution but its not that expensive, can be used to stream any program and its only $20.