jimtherev,
Probably to do with your Imaging Unit / Fuser / Transfer Roller.
Can't remember off the top of my head which one of the three is most likely for streaking..... Google will have to be your friend.
I thought that the mechanism was that the toner was just deposited on the transfer belt with no intermediate step, thence to the paper - in fact, this seems to be the case on inspection of my beestie.
HowStuffWorks "How Laser Printers Work"