I was actually pleasantly surprised when I saw the message in my e-mail inbox that there was a new posting in this thread. For a while now I have been thinking that it might be useful for this thread to get resurected as we 640H (and other Pioneer model users) make adjustments so our machines can still be usable now that we are in the digital era, about to move beyond digital to high definition in two years [the owner of our local cable company told me this last week].
In response to yoru question, the only brand of DVD-RW I have ever used is Sony and I have never had problems as you describe. Like kjbawc, I do not use them that often. My main uses for them are: 1. For programs my neighbor wants to watch that conflict with other programs, like last night when 'Dancing with the Stars,' conflicted with the season premiers (and pilots) for, "Chuck," and, "The Event." The later two were recorded and will be moved to a DVD-RW along with, "Chase," recorded while, "Hawaii Five-O," was watched. I shall be watching the same programs being movd to a DVD-RW from the Pioneer 640H before I erase them (unless I decide I want to record all the episodes and save them). 2. For temporary storage of a series episodes for later editing then burning to DVD-R. "Magnum, P.I.," is one I do as our local chanel jumps around between seasons. I temporarily keep episodes from one season on a DVD-DW.