Ubuntu 11.04 playing audio disconnects USB Hub

Hi ,

I updated my BeagleBoard XM Rev B to the Ubuntu 11.04 Natty (2.6.39-x1).
I am seeing the problem that whenever I play any audio(Any audio of any size),
the whole USB hub gets disconnected. But they get restored once the audio playback is complete.

Also I am using the 5v/3A power adapter.

Have anyone seen such scenarios ?

Thanks
Ashok