If you happened to use Windows Media Player and forgot to uncheck the "Protect My Content" box then your content is protected and should not play.

There is a bit of a misconception about "bought and paid for" vs. "licensing and DRM." For example many thought their "bought and paid for" DVD was free to put onto their PC Share Manager. This is far from clear to most owners. They may need to catch up with licensing and more.

And look at my first sentence where ripping it ourselves can result in locked content unless we are very careful.

--> Don't fret, this is a deep subject. Take it slow.