On Mon, 3 Aug 2020 08:29:34 -0700 (PDT), "
wrote:

You need to understand that the recording medium on an R or RW DVD and on a commercially printed DVD are entirely different. The one is a dye that is 'burnt' by the laser, the other is quite literally stamped. Over time, the dye will deteriorate even by playing - which is via the laser at a lower power than when burning - and become less contrasting. At which point it becomes more difficult for the laser to read it. Not true of a stamped DVD. I have always taken the position that a DVD R or RW is a volatile storage medium, not for the ages, as it is chemical in nature.

Peter Wieck
Melrose Park, PA

I realize that these DVD-R media have a half-life,
however - being unable to detect a blank DVD-R or
DVD-R from multiple vendors probably indicates that
the issue lies outside the media itself.

Don't you agree?

Strongly suspect a Windows issue - though how it could
surface in both a W2K and a W7 system, simultaneously,
is begging belief. I'm concentrating on the W7 system
as priority, as the internet-isolated W2K system has
limited and specific duties that only seldom requires
reading from DVD data.

After 30 years, you'd think that a Disk Operating
System could at least be reliable in operating
disks and in logging/reporting its problems.

Second suspect is laser aging - but you'd think that
would affect writing only, not reading. Seem a lot
of internal DVD rewriters have still to be cleared
from decade-old inventory. Do lasers age wwhen in the
box?

RL