need help - can't play DVD movies

So I can't play any retail DVD movies on my Dell XPS 410. I can play any other disc (CD-R, CD-RW, DVD-r, DVD-RW,etc). I have been in contact with dell support and have tried numerous troubleshooting steps and I have even reached the point to where I reformated my computer and reinstalled windows vista home premium. I have reinstalled my software and have tried VideoLan and roxio cineplayer and that did not solve my problem. I can't even play the movies in WMP or windows media center.
My device manager shows that it recognizes my drive. I have tried dell 32-diagnostics, no errors were indicated. I have also tried uninstalling the device through device manager and restarting my computer. My computer recognizes the device and installs the drivers.

When I insert a retail DVD, I get no response. It doesn't not even show that my computer recognizes the disk.
I don't understand why my computer recognizes all other disks (even burned DVDs), except retail DVD movies.

Here are my specs:

Windows Vista Home premium
Dell XPS 410
DVD/CD Drive: HL-DT-ST DVD+-RW GSA-H31N

Please help me! This is so frustating. Like I have said before I have talked to dell support, more than one representative as a matter of fact. I just get the idea that they don't know what's wrong and so they just keep telling me to do different things

Thanks in advance for any help!

Welcome to Windrivers Leanoh

Have you checked the region that the DVD drive is locked to against the region that the retail DVDs are?

Yes I have both are for the same region.

I would probably push them to replace the optical drive.

Have Dell asked you to update the firmware on the drive? If they have, then yes, get it replaced. If not, post your service tag and I'll look to see if there is an update for you.