Yeah, I tend to agree with Britechguy....sounds like a glitchy DVD drive.
I'm not trying to insult you, I am sure you know how, but here is what I do with WMP and haven't missed yet (this is my canned instruction):
To copy, use Windows Media Player to rip off of the ORIGINAL SOURCE, not a copied and pasted list.
>Open WMP screen
>Upper Right corner, click "Burn"
>Drag & drop the files you list in the left part of the window into the "burn list" on the right side of the window. Then click Start Burn.
WMP will automatically convert to .cda format; it will auto-convert from other file formats when doing the burn process.
The converted/copied files will be auto-saved to the WPM Library as follows:
> open Explore, and at the very top of the menu:
Look through all the folders there, probably will be something like "Unknown Album" or some such. Click on it, the ripped files will be in there.