NEC 3550A Slow burning DVD's & buffer problems

I think my 3550A died - it still burns, but it takes 30-35 minutes at 16X on 16X Verbatim DVD-R’s. The software buffer in Nero stays at 100% but the hardware buffer is all over the place. Also, Windows XP, DVDDecrypter, and other programs will not recognize the drive any more - says ‘no disc inserted’ or ‘disc is blank’. But the burned discs work fine in my other drives. Haven’t changed any hardware or software in many months. The drive is barely a year old, but have burned over 1,000 DVD’s so maybe it’s dead? Anyone seen this problem before?

DMA disabled?