HELP -- DVDROM plays CDs *not* DVDs

[quantass]

System: Windows XP Home, Samsung CDRW/DVD SN-324B, Dell Dimension 8300.

The situation is after an install of Windows Media Player 10 upgrade the friend's PC is unable to read DVD discs. The 2 discs are store bought in this country from Blockbuster and the DVDROM is set to the United States region. There are no scratches or smudges. The DVDROM *is* able to read CDROMs (application discs like WinDVD or Norton) but when we pop in a DVD video disc (ie. Bourne Identity) its as if it is blank -- going to Windows Explorer reveals its contents as blank.

Attempting to play DVDs in Windows Media Player 9, WinDVD, and PowerDVD only results in nothing playing or the message that there is no disc in drive. We've tried formatting/reinstalling Windows XP and STILL the problem is here -- can't read DVDs but can read CDROMs. We've upgraded to DirectX 9.0c. No go. We've tried uninstalling the CDRW/DVD drive from Device Manager and rebooting but no go.

This doesnt make any sense. The DVDROM unit used to work before the WMP10 upgrade and now it doesnt. A format/reinstall should have restored everything. I've tried looking for a driver/firmware update but couldnt find anything.

What can we do to restore DVD playing? Perhaps this has something to do with DRM or DVDROM protection against PC copying and his previous XP install somehow had some software patch for reading?

BTW there are no other pieces of 3rd party software installed on his system besides WinDVD and PowerDVD.

[Nilfennasion]

I'm just picturing another anti-trust suit with the DVD Consortium on one side and Mickeysoft on another, now.