The DVD disc might have been damaged

The DVD disc might have been damaged so as to inhibit playback operation.

I have been seeing this error abit lately.

I dont know what is causing this. I have a Pioneer a06 and have tried several different media to see if that is the problem.
Did not used to have this problem.
Have tried backing up a back up that I did a month or so ago and even that gets the same error.
Tried copying it twice on the fly same error in the same place.
I also have tried reading from the pioneer and a liteon 16X dvd
both have the same problem.

Have done a full format.
Have swore at it and have kicked it.
Replaced the ide cables

But they play on stand alone dvd player fine.
tried 3 differend pc`s and they get the same problem

Duron 800, 20gig hd, 512 ddr ram, gf2 (my second system)
Win xp pro all updates
Pioneer ao6d
Nero 6 and eralier version
Liteon 16X dvd