Fedora Cora 2 Media check fails ?

[abo <titule abo free fr>]

I recently downloaded the CD iso images. Then checked the md5sum, and 
all was OK. And finally burnt the images on CDs (with Nero).
But after I boot the CD, media chack fails for ALL CDs.
So what ? I read a post that told Fedora was picky with some CD drives 
but I tried the check with 3 different drives with the same result.
Can someone tell me what to do now ?

titule.