GSA 4120B and GCE 8160B wont' burn



Hi all,
To my utmost despair, both my dvd burner (firmware A104) and my cd-rw are failing to write. I’m using Nero 6, on XP SP2. Tested on another pc, same story. I loaded an 4120b dvd ram driver, while testing, didn’t work, so I removed that. Is it possible that both hardware are lost? Tested on DVD-R (Prodisc) and CD-R (Philips - also tested the DVD) media with same bad results. The DVD actually burns a slim ring right for the first 15 or 10 seconds (writing Lead in) for both media, but then shows a burn failed message.
What is this? HELP, please!