RCA DCR 8040

I recently purchased an RCA DCR 8040 dvd recorder to save movies off
my DVR. It works good for saving the movies to dvd, but when I go to
play some older movies that I copied using DVDXCopy, most of the time,
the movie freezes. I've tried dvd decrypter and dvd shrink to copy
the movie to my hard drive, and then write them to a dvd, but I still
have the same problem. Movies that I copy from the dvr, and new dvd's
that I've copied with dvd shrink and Nero seem to play fine.
Sometimes, even with the new dvd's that I copy, the player/recorder
(RCA) seems to skip ahead in the movie, and then when I rewind a
little, it will play the scene that I missed. Does this sound like
the dvd/recorder (RCA) is malfunctioning? I use Verbatim dvd blanks.
Any help would be greatly appreciated. TIA

Bob