5) The media is degrading from the edge of the disc towards the inside, or the centrifugal force or simply the increased radius is causing the most "wobble" out near the edge of the disc leading to problems reading the outer-most 50 MB or so. 4) The drive I originally wrote the CD-R on had some quirk which allowed it to read/write out near the edge of the disk but every other drive doesn't follow the same quirk so it has problems.
3) The burner software I used was crap and lied about verification or was only able to verify on the drive on which it was burned (see #4). And if it was crap, why did it verify properly? I haven't noticed any trends yet, but I'll keep looking. Both rated at many times burn speed and 700 MB. However, I used Staples brand, Mitsumi, Maxell, TDK and Philips. The drive I'm using is oriented vertically, the one I burned in was horizontally-mounted. I've tried other drives as well but not had any better luck. So a few things may be happening here (from my limited knowledge of optical drives): 1) The drive I am reading them with is somehow "running out of calibration" sync as it nears the outer-most tracks on the burned CD-R. And I am pretty sure that I had them verify the disc after burn. I don't remember what I used to burn them, it may have either been Nero or Power2Go which came with my ASUS laptop. Many are supposedly 700 MB, so I filled them. I wrote the CD-R's as a single session and closed the discs. Now, almost 5 years later, when I try to copy them back to the hard-drive, it can handle almost everything but the last 40-50 MB. The files were burned in alphabetical order, as a single session and then disc closed. Most of them are getting CRC errors (cyclic redundancy check) *only* on the files that are near the outer-most edge of the disc (the last files written to the disc). I have a problem with many of my older CD-R's and I'm wondering if anyone has noticed the same issue.