Replying to Burning HELP

I just bought some blank cd's with the same specs as the ones I normally use to make music ( 52x , 700MB, 80 min ) but when I go to play my finished cd, only the first 7 or 8 tracks work. After you go past 7 or 8 the tracks freeze and the cd won't play. I don't know why this is happenieng because NERO says "burn process finished sucessfully", and everything seems to be in woking order. Can anyone tell me what the problem could be? Thanks