I have just installed Vista Codec Package 4.5.6 final since Windows Media Player 11 wasn't able to play DVDs.
I now get a different message when inserting a DVD in the drive: "Windows Media Player cannot play DVD video. You might need to adjust your Windows display settings. Open display settings in Control Panel, and then try lowering your screen resolution and color quality settings.".

I don't think the problem is what reportd in the messsage. Any idea what it could be?

Thank you.

Oskar.

That pack does not contain a proper decoder for DVD video.

Uninstall it and install the K-Lite Codec Pack. That is much better.