whats wrong with my dvd-writes?

i have a benq 1640 (f/w bslb) thats always done better with +r. then while back some -r's when i burnt movies would cause pixelation/dead pixels type thing in the picture so i stuck to +r.
it was always had issue of reading the dvds that it burnt even some +r (in windows explorer; on my dvd player things were fine)
of late while the burnt dvds play ok on my dvd player and most discs show up on explorer, when i do nero scan disc quality test it gives Quality score of 0!
at first i thought it was batch of moser baer +r so i called for verbatim +r from KMD and same issue - things seems to play fine (havent played all movies on it but whatever i have is ok) but QS is 0.
so should i let it be or what is the issue
thanx guys





no one?? anyone??