Unable to prepare data for recording : Failed to get disk contect

Hi Guys,
Im having a problem trying to burn to a DL DVD

I have created a project using Nero Express 3 (A grand prix race, which I hace captured from video onto PC), and I am trying to burn that project to a DVD+L DL disk. I have attempted this before with other projects, onto a DVD+D DL,with no problems, but I think I cannot seem to do this project as it is bigger than the rest (Anything over 5gb seems to be problem).
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After creating my chapters, and moving onto the next screen,the following message appears :
“Your project currently exceeds the capacity of a normal DVD,but still fits onto a DVD-9 disk. You need a DVD-9 media to record your project on.
Do you want to have the project quality reduced automatically so that your project will fit into the available space.
If you click No,the project will be expanded to DVD-9”
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I click No, then click on next a couple of times, to get onto the"Burn Options" screen.
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There, a similar message appears :
“Your project currently exceeds to capacity of a normal DVD, but still fits onto a DVD-9 disk. You need a DVD-9 media to record your project on”
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It also tells me the ‘Used disk space’ for this file is 7.79GB
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I click on ‘Burn’ and the following message appears :
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“Recording this project may be unsuccessfull and could produce unstable results. Do you still want to start recording”. (When I have previously had successful burns on the DVD+D DL, with smaller files, I have still seen this message)
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I click Yes, and it transcodes the entire project (I think), but just when it is about to start writing it to disk, the following error message appears :
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“Unable to prepare data for recording : Failed to get disk contect”
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As I say, I have tried several projects, and it seems that anything over the 5 and a half GB size exhibits the above problem.

Im using Windows XP
Plextor 716A DVD Writer
Ive updated the latest 4 updates from Nero.

Have you tried transcoding to a folder first, then writing to disc?

No, have not tried that, though in the Burn Options screen, it does default to a folder for saving, rather than a DVD.
Is it just a case of letting it save into the folder, then copy the file onto the DVD ?

Many Thanks,
Richard