what software are you using to burn?
what os are you using?
some burning sofware have the avility to verify the burning and make sure that the dvdr is actually readable. sometimes a bad burning can happen if your dvd disc has dust on it.
winxp pro sp1
amd athlon xp 2400+
1.5 gb ram PC2100
NVIDIA GeForce4 Ti 4200 128 mb
SOYO KT333 DRAGON Ultra Platinum
80gb WD
120 gb WD