Freeze afer USB playback starts (Frodo)

Hi

Has anybody noticed that Video playback from an external USB device freezes after a few moments in OpenElec 3 (Frodo) and does not return. The Pi does not freeze and the stop button can be pressed on the remote and the menu is displayed.

I have turned on debugging and tailed the error logs during playback, I didn't notice anything obvious on the moment of freeze.

Video playback via NFS is ok on both PI's as is streaming content over the internet (tested with iPlayer / TVCatchp playback)

I am resisting submitting a bug until I asked the question here.

Thanks