Join Date: May 2002
Location: Toronto, Rogers, 9865 & 8300-eHDD, Sharp LC75N8000U, Denon AVR4310Ci; Sony KDL40W3000, 9865
Your reasoning in the last paragraph may be faulty. Quite a few of the upconverting DVD players do not have an HDCP compliance requirement since they're not truly HD.
Since the TV has an HDMI input, those are usually HDCP compliant, so I guess it could be an issue with the STB. Turn on the TV first, then the STB.