Pioneer 106 leave rings on my dvd disk

i got a new pioneer 106d but when you burn dvd on it at 4x
it leaves a dark ring in the middle of the disk ,as if the laser changed its power during the writing

it works fine at 2x
i use mirror platinum 4x dvd-r 4.7 gb
and yes i have tryed using other disk and its the same
burn fine at 2x
but leaves a ring in the midle at 4x

work ok burning cdr at any speed
i got another pioneer 106d v1.7 in a diffance pc that works fine

nero 6.001
dvd x copy
win xp
1300 duron
256 ddr
pioneer 106d v1.7 using dma
email me