I would submit (after having the same problems myself as newgamer) that Windows XP will not play copyrighted DVDs on systems with graphic cards with TV outputs and using software decoding. I would further submit that Macromedia copyright protection is the culprit.
Now for the circumstances. I have a brand new Windows XP system with a very fast Intel HyperThreading processor, NVidia GeForce3 500ti video, a combo DVD/CDR/CDRW drive and 1Gb of memory. Now You would think that this system would Kick Ass. It does. But it won't play a copyrighted DVD.
I put in a older DVD "Amadeus" and it plaved beautifully.
I have tried everything. I have turned off the HyperThreading. No change. All drivers are current but may be a bit juvenile. I have tried a myriad of differernt players.(MGI SoftDVD MAX,PowerDVD3, NVDVD,WinDVD) I get errors like "no disk detected","disk may be damaged or dirty or otherwise inhibits playback"(Hell that time it was a brand new disk right out of the package). Or they just crash.PowerDVD gave me a numbered error That I tracked down to being Macromedia related. I downloaded a program that circumvents Macromedia. DVDIdle. I then ran "Star Wars Episode 2" in PowerDVD and it played the FBI warning screen that's at the beginning of all recorded video then the producer video splahses and then it hangs. The same happened to "Men in Black II". But I can put in an older film such as "The Good the Bad and the Ugly" and no problems.
DMA issues are not a problem since my DVD drive runs in mode3 and has 8Mb of casche ram.
To test my theory I installed Windows 98 on alternate hard drive and ran "Star Wars Episode 2" in WinDVD and Had no Problems.
So again I submit that Microsoft XP will sabotage your attempts to play copyrighted DVDs.
If anybody has a solution to this vexing issue I would be grateful and so would Microsoft. I smell a class action lawsuit.