DVD Burn Failed-Matshita DVD-R UJ-815


Please help: I can not burn any DVDs. I am trying to burn some pictures from iPhoto to DVD for storage. I choose the pictures & then hit the burn icon at the bottom of iPhoto. It will run for about an hour but then stops. I keep getting "Burn Failed: the burn to the MATSHITA DVD-R UJ-815 drive failed. Unknown error." I've tried several TDK DVD-R 2x discs & the original Apple DVD-R that shipped with my computer. I am able to burn CDs with no problem but this is the first time I've tried to burn a DVD. Can you also tell me if I will be able to use TDK DVD-R 8x since I can't hardly find 2x or 4x anymore. Thanks to anyone for any help. I have lots of pictures & I've got to get them off of my computer. Thank you very much. :)
Apple PowerBook Titanium G4 15"
purchased 12-2-02 from MacConnection.com
Mac OS 10.2.8 (6R73)
Matshita DVD-R UJ-815