Strange DVD data write problem?

hi all !. . I am new here and .my problem is i wanted to back up my mp3 collection from my hd so i wrote them out to 3 dvd-r's with the roxio creator 10. It took a while because i had over 1000 mp3's to back up. I din't do any compression or anything. .i just wrote them to discs. Well after the 3rd one was written i checked and dvd # 1 looked fine with about 400 mp3s on it but from past experience i never just "look" at the data.. . So i started to play them for a test in alphabetical order . . 1-25 played back fine . .but 26 would not and then more bad one 1 plays and then 5 badones. . . Ect.. . Until until by #70 no more on the disc would play leaving some 300 bad files ! . .. Strange. . But at least i did not delete any of the originals yet( by tyhe way all of those played just fine )
so the writing must have somehow corrupted the backups . So then i decided to check the other two discs . .. All played absolutly perfect on the other two dvds??? The only thing i noticed is taht
roxio has something called "retrieve"?? Which pooped right up when i put disc 2 & 3 back into the dvd writer drive . Anybody got any idea what is going on with this situation .. .i will go back and try to write the bad ones again . . . Any help is greatly appriciated. . .
Thank you . . . . . .jerryuuc@[redacted].com is my email
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