These are the silvery factory made type DVDs so on their DV9000 and my DV6000 series I don't have any issue at all with factory made DL DVDs.
The issue is not common and it's time for you to call HP to have it fixed.
Bob
I've had this problem on two computers running Vista, though re-booting works with my desktop, my notebook is DOA with Dual Layer DVDs.
Here's the thing, a lot of people have run into, you put a disk into a drive on a Vista computer and you get "this disk needs to be formatted" or "please insert disk into drive." This issue seems most common with DL DVDs.
I have two systems, one is my tower, Vista Home Premium x64, which I built using an ASUS MOBO, a Phenom Black 2.6x4 CPU, 8gig of OCZ (4X2gig) with an Sapphire HD PCI-E card, it has an HP DVD-DL RW and a Sony DVD-DL RW DVD drives. Both, occasionally refuse to read DL-DVD's, but a re-boot fixes every time and it hardly ever happens.
My other is my notebook, a Custom HP DV9000 CTO with 2X320gig HDD, 4 gig ram, and a GeForce 7060 graphics GPU. It has a DL burner with Lightscribe. When I insert ANY DL DVD, movie, data, burned, or Game it refuses to read it and ask me to format.
I tried reinstalling, I tried swapping HD, I tried turning off and on autoplay, changing registry settings, but it seems a little feature that allows live disk drag & drop burning in vista is something that CANNOT be turned off or uninstalled and this feature is what wants me to "format" my disk.
Any ideas???

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