My sling box 500 is connected to my direct tv at my home. I'm trying to watch some tv on my phone while using the sling player app which worked fine yesterday. Now today, every channel says the "your TV cannot display due to content protection. Use component cables..."
Looks like your TV provider has implemented HDCP to stop you recording (and slinging) HD content. You will have to do what it says and ditch your HDMI cable and feed the TV from the component OUT plugs on the Slingbox.