I believe it it the BB Media Player. I just recently updated my BB 8330 to 4.5.0.127. Before I did, Moodio.fm was hit and miss. I was also unable to close the media player while a stream was playing. If I did, the stream would quite. Since the upgrade, I am able to close the media player during a stream and continue listening. I have also had no problems getting the stream to work.

In the recent BB OS Upgrade they must have done some work to the Media Player.