low quality burner?
despite the fact that its supposed to be Digital, and a perfect copy, when burning really fast errors are more prone to creeping in. most arnt noticable, or the 'noise' is filtered out as the signal recieved is binary. if the noise is bad enough though the pits and 'not pits' on the cd get progressivly blurred and u get corrupted data cd's and bad audio tracks.
i.e. the faster it goes the less time the burning laser has to create a sharp destinct pit in the CD surface. also compounded if the drive quality isnt too great and there is a weak laser in use.
infact some audiophiles dont burn cd's at anything greater than 2x or 4x becuaze of this, and when making extra long cd's its also reccomended you use the slowest possible burn speed.
overall it depends on the build quality of the drive and the media your using.
slow it down, try higher quality 'gold' cd's, or get a new drive.
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