When I first got my Photobridge I spent weeks trying to fix problems with video and audio play. I tried new firmware, Mplay software, etc. It started working and worked well for over a year. I wan't sure what fixed the problem.
Well, the problem reoccurred and once again I went the firmware/software route. This time it didn't work. I noticed that my standard definition files would play okay, but my high definition files wouldn't. This sounded like a data rate problem.
I noticed that the Full Duplex lights on my Linksys router were off. I tried unplugging and pluggin-in the power cord on the Linksys, the Full Duplex lights annunciated and the playback problems were fixed.
I've read dozens of topics regarding this type of problem with the PB and I've seen responses pointing to the routers....but not the full duplex mode. Maybe I should have figured it out earlier, but now I can now see the little LEDs glowing on the front of my router and I'm at peace with my Roku.