As others have stated, this is likely the disc itself.
Here is the explanation:
The "tracks" on the disc are circular similar to a record (if you recall those...). If you look at the non-label side, you will likely see some scratches. This is usually OK since there is error correction built into the digital information on the disc. If the scratches are circular, in other words, go around the entire disc, there will be too many errors for the correction algorithms to correct. The disc won't read. Also, when a disc is first started, the laser will fire in an attempt to detect a disc. Once detected, an attempt will be made to read the TOC (table of contents) of the disc. This is read from the "home" position which means that the laser assembly does not need to move yet. Once this has been read, the laser will be moved along the rails as more information is required to be read.
In your specific case, I would suspect circular scratches which are preventing the disc from correctly reading the data.
Hope this helps,
Dan
P.S. If you want to clean a disc, use a damp cloth and wipe from the center hole to the outside. Do NOT go around the disc, EVER!!