Hi, I have a Lite-On LDW-451S and I recently puchased a large amount of cheap media, I proceeded to make a few burns and everything seemed ok, however after a couple of burns the system started rejecting the discs that I had burned, the system will not mount the discs and will not allow me to access them. My questions is: How common is it for a DVD Burner to be able to write a disc but then turn around and not be able to read that very same disc? Can this be caused by a dirty laser lens? The burner is less than 1 year old. Thankyou.