Burning Music Into CD-R's Messed Up.?

WHY DO MY BLACK CD-R DISK KEEP MESSING UP WHILE IM IN THE PROSSES OF BUNING MUSIC ON THEM??I WENT TRU HALF A PACK OF BLANK CDS BECAUSE THEY KEEPT MESSING UP...WHEN ITUNES WOULD START TO BURN THE DISK, 3 SONGS LATER IT WOULD CANCEL THE DISK MAKING IT TRASH BECAUSE IT COULDNT BE USED....THIS WAS A WAISTE OF CDS DOES ANYBODY KNOW WHY THIS HAPPENES???