I'm sorry about the double post, I'm using a dual boot ubuntu 9, and windows 7 system, , and getting the same issues in both. Keep in mind this problem started while I was running XP Pro on a legit licence. I'm currently using the windows 7 RC from technet, they've got a free 1 year licence, and the way I reinstall all the time it works for me. Unfortunately can't run sony's drivecheck that their tech support recommended. Until I can get around to trying it on an xp machine.
Back to the issue. I can read and write DVD's including dual layer just fine. I can not read or write any dvd's with my dru-710a, I have sucessfully installed the newest firmware recommended by sony.