I have been testing all my copies on my Toshiba laptop.
I have mentioned this before , I am using Nero Speed because that is the only program that will work with the DVD drive. And the only test it will do is the ScanDisc Read Test. Any other test I try it says the drive does not support it. And of the five brands of media I have tried it would only identify one.
I bought an LG-GSAE40L External Drive the other day hoping I could do better testing.
With it and Nero I can get the disc MID and the same Scan Disc Read Test and much faster but now I can't even try the other tests. When I try DiscQuality it doesn't even allow me to try, the start button is not highlighted.
And the same for the ScanDisc C1/C2-PI/PO. At least before it said drive does not support.
Can anyone tell me what I could be doing wrong.
Should the new drive be okay or should I get something different.
And what tests should I be doing and why.

Thank you

Just to add to this, I just tested a dvd I dubbed from my EH-75.
I tested it 2 times on the internal drive and it was excellent.
I tested it 2 times on the External LG and it flunked bad.
It plays well in the Panasonic but is unwatchable on a Coby.
What does this mean?

At www.dvdinfopro.com you can download software made by Nic Wilson that will give you info on you DVDs and also you burner. I haven't been at the site for quite a while, but I checked it now, still in bidiness. The free software used to come with ads.

LG drives can't do quality testing. The best ones that are easily available to do pretty decent quality scans are LiteOns, and the drives based on LiteOn builds (such as some Sony models)

Keep in mind a quality scan is a snapshot of how THAT disc can be read in THAT drive at THAT moment. Different drives, even of the same model, may have different results.

As for why a disc won't read in a Coby, it's possible the drive is bad, and/or the Coby simply doesn't like that media. If you burned to a DVD+R, try using a DVD-R, and vice-versa. And always use the best media you can-- my experience is set-top DVD recorders are NOT excellent burners and usually produce discs with much higher errors than PC-based recorders.

Some excellant ideas above..

I assume you are talkiong about DVDs from a standalone DVD recorder....

My Pioneer 640 DVD recorder has a Pioneer burner and its' high speed DVD burns on Verbatium media test well (CD-speed) on my PC using a Lite-On internal drive. In my experience, real time DVD recorder burn quality has been less consistant.

I have used other Recorders/media combinations that test as poor burns, but will still play in most newer DVD players. Poor burns tend to freeze/skip as they near the end of the disc.

I burn almost everything of value in video mode to a quality DVD+R or -R format disc. Some older DVD players don't like VR mode or other combinations of writable media and/or format. My media/format of choice (for wide playability) is Verbatium 16X DVD+R bitset to DVD-Rom.

Always Suspect;
First, the media quality .... (come on, if its worth burning what's an addition $.10 - $.15 per disc?)....
Second, the format used...
Third, the burner/software...

as always YMMV ;)

Does anyone have specific brands & model numbers of DVD drives that will do quality testing?
Either internal or external.

I figure if I'm going to add a DVD burner to my PC it may as well be one that will allow me to check the DVDs that I made on the DVD recorder.

Does anyone have specific brands & model numbers of DVD drives that will do quality testing?
Either internal or external.

I figure if I'm going to add a DVD burner to my PC it may as well be one that will allow me to check the DVDs that I made on the DVD recorder.

Several will do it, but with varying results. LiteOn is the only brand that is specifically built for this, although any burner with a Mediatek chipset can do it, and some others too.

Keep in mind that scanning for PI/PIF errors is not a qualitative measurement of burn quality. It's a method of A-B comparison of burns to see which is "better" than the other. There are a dozen variables at play in how well a disc scans. there's also a wealth of mis-information around on what the errors mean or measure. Best to just use any tests to determine what media gives the best results in a specific combination of burning drive and scanning drive, and don't try to understand why. Less is better, is the main thing. Some folks prefer to just do a transfer rate test in CDSpeed, and if the disc reads at full speed, consider it "OK".