Roxio is not as bad as some members here think. I've used it for years without much problem.
We need to find out if it's Roxio's burning engine causing the problem or the hardware/media combination.
Are you using DirectCD/DragToDisk (can't remember just when the name changed) & formatting the DVD+RWs with that or are you creating a data disc on an RW?
Precisely what DVD burner do you have & was Roxio supplied with it?
Obtain
Nero's CD-DVD Speed & get the Media ID of the Sony's. That'll be the Disc Info tab in this app.
Relying on RW media for a secure archive is really very dangerous. I've had serious failures in the past with CD-RW media & wouldn't risk it again. DVD+R/-R is much safer.