Vista - Vista MCE x64 wont play DVD but VLC will!

This problem has been driving me nuts for the last couple days as I have been unable to find a solution!

My Vista Ultimate x64 will not play DVD's in Media Center OR Media Player. VLC will play DVD's- No problem!

I thought it might be the video card so I changed it-No change.
Performed all updates-No Change
Did a clean install-No Change
Tried a different monitor-No Change

Hardware:
Asus P5Q-EM
Intel E8400 3Ghz Core 2 Duo
4GB ram (2 sticks total) Corsair memory
Vista X64 Ultimate

Before the clean install I also tried different codec packs and the Nvidia PureVideo decoder also with No Change

Media Player gives the error that there is an error with my digital copy protection between my DVD drive, decoder and video card. Media Center says it Can't play the DVD due to the DVD being in use by another program, the resolution being wrong or the output not possibly being compatable.

The DVD player is not being used, the resolution is 1024X768 and the output is VGA (analog).

A further interesting phenomenon is that if I play the DVD using VLC media player, THEN Media Center will play the DVD but the video will be broken and very choppy and very delayed while the sound goes smooth. Something is very wrong.

I also tried resetting the DRM and did so successfully but also No Change in behavior.

I'm not sure what else I can do. Can you (or anyone) offer some help or suggestions going forward?

I appreciate any help and thanks,

Leif

Since VLC will play the DVD my guess is the codec. VLC player comes with its own codecs and will play virtually anything. If you have a copy of WinDVD or PowerDVD, both come with a good DVD codec and WMP will use that codec after you install either of them. I'm thinking it wouldn't be the DRM unless you are playing a Blu-Ray disk.

Problem solved- It was the FIRMWARE of the NEC DVD drive. I had installed some grey market firmware to optimize burning speed and never thought it would affect DVD playback...but it did.