I have been having this issue with my wifi and havent found a solution for it yet. I listen to music streams likes pandora and XiiaLive, but shortly after my screen turns off the wifi disconnects and the music stops to rebuffer with 3G. Once I turn my screen back on, the music stops again to reconnect to the wifi and rebuffer. A half hour of this and it gets pretty annoying. I like to use wifi rather than 3G when available. I have my wifi sleep policy set to never. This is not router specific and happens on any wireless that I am connected to.