iTunes purchased HD movies won't play - HDCP error

I've purchased HD movies on iTunes but they won't play on my Windows PC. I'm being given an error about HDCP support.

The "Learn More" button takes me to this link: iTunes for Windows: Unable to view or play HD video content that requires HDCP - Apple Support

My computer has a built-in display. It's an "all-in-one" PC so the movie should play.

How do I fix this?