Sony Dru-800a problem

I have been having a weird problem with my dru-800a, I can read all dvds burnt prior to a certain date (I can read dvds I burnt before and commericial dvds), I can no longer write dvds as they are full of errors and the drive will not read them after they are ejected, other computers can read them but they have many errors on them; after being ejected and reinserted into the burner they appear as Blank CDs. My Cds read and write perfectly fine. I have tried different brands of media Memorex and Verbatim, even though I was using discs from the same spindle before and having no problems. I haven’t installed any new hardware or software, nothing else is running on the same IDE channel. I tried removing the drive and restarting, removing the secondary ide channel and restarting. I am running the newest service pack of windows XP, and firmware verision KY06. Device Manager says everything is fine. I have tried switching to PIO mode, but that only prevents the drive from wanting to burn at all. Sony of course hasn’t been much help always suggesting things I told them I already did. Everytime I find someone else that has a problem similar on any other forum all that is replied is either nothing or “I found the answer somewhere else,” not bothering to leave what they did.

DMA: Mode 4