Cyclic Redundancy Check

These have become the words of death for me.  What does it mean, and how can I avoid it?  When I burn large files, they're USUALLY ok, but if I burn a DVD full of many small files (say, roms or mp3's) it's almost GUARANTEED I will get the good ol' Cyclic Redundancy Check on at least some of them.  I took this to mean that some of the DVD's were corrupted during burning or something, but they all verified ok--what's the deal?

I'm using Nero 7 with a Sony DVD-RW drive.