I, too, am glad I found this thread when I was trying to figure out what was wrong with my Panasonic DMR-E50. I had called Panasonic and they sent me a firmware update. I thought it did the trick, but then it didn't. Never connected that my freezing issue was only with commercial DVDs.
While I have a DirectTv Satellite Receiver plugged directly into the back of my DVD Recorder, I have temporarily had to have cable TV instead of satellite. Rather than unplug the cables in the back, (I don't want to dig around in that mess!) I simply plugged my Scientific Atlanta Explorer 8000 HD into the front input panel of the recorder.
Lo and behold, taking the Scientific Atlanta cable box out my recorder altogether has solved the problem. I hope I'll still be able to burn items that are on that DVR box, though. It seems like the problem is only with commercial DVDs.
So, if you're like me and simply Googled "Panasonic DVR Recorder Malfunction" and ended up in this forum, congratulations. Get rid of your Scientific Atlanta piece of garbage and you're home free.