Sounds like either a serious problem with the cam needing servicing or some kind of fatal corruption on the DVD for whatever reason.

So lets take first things first.
Take the disc out of the cam.
Download and install the trial version of Nero 8.
Place the unfinalized disc into the computer DVD tray. Open Nero 8 StartSmart.
Click "create and edit" at the top of the screen.
Click "author, edit and capture video." NeroVision 5 will start.
Click on the disk tools drop down menu then click "finalize disk."
In the option box that appears choose "no menus" and let it run. Hopefully you now have a fully finalized disc that is readable.
Let me know how that part goes.

For the cam, put in a new disc and see if it behaving normally. Also please do not tell me you are using RW discs.

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