WD TV Live Plus Limited Public Beta Firmware Version 1.4.18_B (1/13/2011)

I have this problem with the final .17 too. Mine locks up on the internal HD with some of my ISO videos. I would hit back or menu and it is a 40% shot where it will delay 1-2 minutes to respond or never respond (requires unplugging it). The power button would not work to shut it down. This happens without even pausing the movie.