DVD Drive Problem

[NarutoNamikaze]

My system specs are:

Windows Vista Ultimate SP2 32-bit
2GB RAM
nVIDIA Geforce 9400GT
Seagate Barracuda 500 GB HDD
Sony Optiarc DVD RW AD-7240S ATA Drive (Its a new drive that I recently purchased)
Nero 9 Essentials

I burnt two DVDs successfully using Nero 6. When I burnt 4 more DVDs, the burning process stuck at 1% at the lead in process. When I checked the taskmanager, it was running fine. There was no Not Responding Message. I waited for 5 mins and it was stuck at 1%. Then I stopped the burning process and the DVD was no longer usable. There was just 1 fine circle of burning on the DVD. In the Device manager, it showed that the device was working properly. I thought it was because Nero 6 had compatibility issues with Vista, so I upgraded to Nero 9 Free Version. Then I wrote 6 DVDs. It was successfully burnt. Then again the same problem occurred with 2 more DVDs. Is the problem with Nero or my DVD Drive?

I have used various media like moserbaer, sony, frontech, national etc. Its writes successfully even on National Dual Layer. Haven't got the error when writing dual layer till now but i don't want to take a risk and waste it.

I burn videos using the data disc option. Is it the problem? Should I have used the DVD Video option? It was always fine when i burnt DVDs in Win XP with this option. Plus there's only Data Burning option in Nero 9 essentials. Plus all the succesfull burns were with the Data DVD option.

I also want to know how to update the firmware.

Thanks for any solution in advance:-P