It means only that the laptop drive is able to read the media with all its errors and the Plextor cannot. That’s all. Whether it is because the laptop is reading at a slower RPM, using higher laser power, has better error correction, reflectivity of the disc is not a factor, or whatever else, you are able to extract the archive on the laptop. Good on ya! If you want to be able to read it on the Plextor, and have a longer lived archive, I’m only suggesting that you extract the file on your ROM and then reburn it on to quality media. The question is not whether CMC is readable in your lap top…it is…the question is whether you could trust the CMC to be archival quality and be error free in the future. It is apparently not now error free and will probably degrade from here. Better to just reburn on a good quality disc and then PI/PO to verify burn quality.