Pioneer DVR-108 can't burn at 6x or higher

i have tried every media possible.

i burn 6x speed on a 8 speed dvd 3 times out of 10 the pc hangs if i burn anything higher then 4x speed.

what causes this problem

have the latest firmware.

Your hardware. Post a log, use decent media, get rid of heat in the computer, use a strong PSU and good IDE cables.