trouble reading dvd-r with nec nd 3520A

[kalleboy]

i´ve resently changed my old dvd writer (nd 2500) to a nd 3520A. everything was going fine until the other day. now it´s having trouble reading some of my "old" dvd-r. funny thing is it´s only some of them it wont read. some of the dvd-r i´ve burned with the nd 3520A is also showing up blank, even though they play fine in my dvd player. i´m using prodye dvd-r 8x speed gold disck, and has never experienced any problems with them. i burn all dvd-r with nero 6.6.0.1 wich has worked fine for me until now.

i can´t think of anything that´s changed in my OS apart from getting the new burner, so if anyone has any ideas i´ll be very happy to try them out