I am having tons of problems with playback with my BD670 - with both BD and DVD disks. There are tons of black screens, and audio drops. Turning the unit off will sometimes fix it, but it is hard to explain to a 3 year old why his video keeps stoping.
I finally relented and allowed for the updated firmware 2 weeks ago, and it seemed to work a bit better.
I have done some searches and read tons of this thread, but haven't seen mention of my exact problem - or if there are any solutions. I guess there is an even newer update available I will check for tonight.
One other problem I have had is it won't recognize any disks on occasion unless the unit is powered off for 10 seconds or so.
I haven't even used the apps as my TV has them and my DTV box has them also...