From what I have read in other forums, if you use HDMI cables anywhere in your setup with devices that can connect back to the Slingbox then you are always at risk of the HDCP taking effect be it immediately or after 3 months or after ???? The simplest workaround is to use component cables to deliver your HD video signals.
Chakkarinen is right; some devices, like DVD players and digital set-top boxes, have copy-protection built in to their hardware. One copy-protection system that’s commonly used is HDCP (High-bandwidth Digital Content Protection, also known as HD Content Protection). HDCP first detects that digital information is going through a digital connection, like HDMI. Then it interferes with information going through any other audio or video connection to any other device. You can find more information about this trouble here: