Strange NEC3500 reading problem

Hi,

I've been encountering some strange reading problems with my new NEC 3500A. It reads most of the DVDs perfectly (including many scratched up ones). However, it refuses to play, or even recognize certain DVDs (each of the DVDs are different, not limited to any particular brand).

The strange part is, these DVDs are in immaculate condition, and play perfectly on my PS2.

My drive's housed in a Plumax USB2.0 External enclosure. Any idea what may be causing the problem?

what is the pattern? are they all -r, +r
what are the mid codes?
what software used to burn them?
if you copy them to another brand of disc or even the same brand is there any change?

Well, one group is a set of pressed DVD-ROMs (Golden Surface). Most of those DVDs run without any prob, but a few of them refuse to run.

Another set of them are -Rs. These are some generic brand, with Manufacturer ID DKMZ01. They were created with Nero. Also, copying to another media does solve the problem.

I have had that problem too, not just with this drive. It has to do with a firmware and media combo. that just won't agree with each other. Thats why re-copying to a different media fixes it. Its nothing to worry about, but using high quality media usually wont cause this to happen with any firmware.

Thanks m8! It had me worried for a while.

Sorry I should have said that it can still happen with high grade media. It is more of a FW issue than media but it tends to happen more with cheaper media. For example I have some 8xTY that wont be recognized on my BenQ 1610 if they were used to copy a dvd in my pioneer 109 (w/ FW1.40). I dont know WHY exactly it happens, beyond what I know already.