Help with DVD Burning, please

[#1]

After several months of trouble-free burning of dual-layer DVDs I have hit a problem for which I cannot find a solution.
I had not changed my media, upgraded firmware or changed software but, suddenly, all attempts to burn to DL printable discs is failing with an error:
Could not perform end of Disc-at-once
This happens around halfway through the burn.
On advice from Ahead I have uninstalled Nero 7, rebooted, ran the cleantools, etc. rebooted. I then installed the latest version of Nero 7 yet still the problem persists. So far, 5 wasted discs.
I attempted to update the firmware for my Sony AWG170A but that has failed, too. Sony sent me a OEM vesrion which also failed to update. Not really sure a firmware update would be necessary.
Strange thing is that I have no problems burning CD (80 min) or single-layer DVDs.
Has anyone else experienced similar and found a solution?
Oh, I have been using Nero Vision to created a .nrg file then burning with Nero Express (as I said, using this method for several months without issue).
TIA

[#2]

I had exactly the same problem and went through all sorts of hoops, in the end I swapped in another drive and the problem went away.
You may have a different problem but if you had another drive you could swap in or borrow one for a day to test it would certainly rule that in or out.
God...

[#3]

How are you burning the image? If you copy a dvd then it can be  something taking over the CPU at the critical time even AV.
I would try creating an image and then burning the image as the  image takes all the cpu usage creating the image but very little when burning.
Next check the dma setting first make sure the drive is using DMA and stop any device you dont use from using DMA. If you only print via USB disable the printer port in the bios as that uses dma
Other things to check is the HD defragmented been checked for errors anything using a high CPU

[#4]

Hi Samuria.
Already done all you suggested.
Actually, I always use Nero Vison to create an .nrg file then burn that with Nero Express. As I said, no previous problems.
I have tried to think of any changes I have made recently and the only thing I can think of is I installed Virtual Daemon Manager V4.09HE.
Does anyone know if that can cause conficts?

[#5]

It might do - DaemonTools does tend to install some drivers, including those for virtual drives which shouldn't muck with things but sometimes can do. It shouldn't be a big job to uninstall it to test.
If it doesn't turn out to be that it might be worth trying a lens cleaner on the DVD burner - has made a difference for me in the past. Just a thought though.
Hope this helps,

[#6]

Problem now solved!!!
I unistalled Daemon Tools and successfully burned a dual-layer DVD without any issues.
Thanks for the advice.

[#7]

It also installs some lovely adware I believe. Which is nice.

[#8]

I never noticed anything being picked up with SpyBot Search & Destroy or AdAware SE.
I will avoid it like the plague in future.

[#9]

*Thumbs up* Glad you got it sorted!