I've gone thru 2 15-pc spindles of Memorex DL with my Plextor burner.
The first spindle had about 2-3 coasters in it and the 2nd had 12 coasters.
I only got 3 good burns out of 15. A 50% failure rate!
It didn't matter whether I used Nero or DVD Decrypter (I found creating
an ISO file and burn using Decrypter to be better than burning w/ Nero),
the burn would "succeed" but the subsequent verify would always fail
at between 59% - 61%. There was obviously a manufacturing error since
it is the exact same failure on all the disks.
Never again will I get them!!!