What is CD rot?It was discovered that some CDs can have the reflective layer begin oxidizing. This interferes with the reflective quality and screws things up for the laser to accurately read the disk. Since it is oxidation, it usually starts at the outer edge of the CD - that's where the final tracks are located. Disks that are longer are more susceptible since they run tracks closer to the edge.
This is really a quality control issue at the manufacturing level (which can affect any product in any industry. Remember some of the absolutely horrid quality LP records that were released?)
Your best bet to salvage things is to use a program like EAC (Exact Audio Copy) with the error correction turned on. See if you can rip the CD to your hard drive and then burn it to a CDR. If that doesn't work, your only real alternative is to buy another copy of the disk.