Panasonic DMR-E50 Recordings

Here’s the issue:

[LEFT]Panasonic DMR-E50. Recordings appear to record without any issue regardless of source (video tape, TV/Satellite feed, camcorder) but playback has a big problem.
The playback starts out fine, however at the 1 hour (+/-) mark the recording begins to break up (video and audio) and progressively gets worse until the machine locks up in total freeze frame, typically prior to 1Hr 20 min. I’ve tried playing back the DVD’s on other machines with the same ultimate result - digital breakup and lockup. Also same result playing back on either of my desktop computers and laptop. All the DVDs are -R formats (Panasonic requirement) and are “finalized” typically I use SONY or Memorex discs. Here’s a little twist: non-finalized recordings play great but (by definition) only on the DMR-E50. DVD-RAM recordings also seem fime but again are limited in playback compatability. One last bit of info - the machine plays commercial DVDs perfectly.[/LEFT]

Question - has anyone experienced this breakdown and is there a known root cause or should I be talking directly to Panasonic?

Hate to dump the machine but need the reliability that I thought I bought.

Thanks for any feedback…