Problem when burning LG disks with Ricoh 7200a

I have a curious problem.When burning cd’s with Ricoh 7200a at x20 speed using clonecd or nero the burning process is being stopped a couple of times,and then resumed.The disks don’t get messed up,just the burning process is longer that it is supposed to be (5 minutes for 700Mb @x20).The media is supposed to be 40x burning compatible.I am using winXP pro SP1.
Have any guesses anyone?Just bad media?The Lg disks by the way are PRODISK inside.