Pioner replaced my 109 with another model, and now I find that when I burn a DVD-R (8x TDK burned in Toast 7 on a Macintosh) the discs all play back just fine in my stand alone DVD player, but a number of them won't play in my computer. In fact the computer simply spits them out. It's consistant about which discs it doesn't like, but inconsitant about which will work or not once written to.
I've set my system preferences to mount a blank DVD, so it's not that it sees it as unwritten. It simply doesn't like the disc. I've recorded with this media in the past with no problem, so the issue is either with Toast 7 or the replacement drive (which might be a refurb).
CDs appear to not have this problem.