New to all

Hi all
I have just started doing DVDs.
My first lot went OK on DVD+r with litescribe.
and play ok on a Lenoxx DVD 8600 stand alone player
using a Lite-on DVDRW SHW-1635s burner.

my problems started when i started using TDK DVD-r 1-16x DVD's
they seem to recoder ok at 6x but when I try to play them on my stand alone player they freez in some places and will not continue.

Nero 6
shrink 3.2

any tips as to what is wrong.
Andrew