Pioneer DVD RW DVR-109...recognizing burned DVDs

I have had the DVR-109 for about 2 years, bought it new and installed it on my Dell Optiplex. I have had little to no problems copying and burning dvds with it, and the copies work great in my stand alone players, but recently, it has been giving me real issues. It has no problem recognizing store bought dvds, and in the past, burned dvds too. But now, when I put any burned DVD in, I get....nothing, absolutely nothing, try to play the DVD and it says "no disc". I explore the DVD and there appears to be nothing on it. Is this a driver issue, firmware, or has it crapped out? please help. thanks