There have been many issues going "through" an A/V Receiver, because of firmware incompatibilities. You probably need to connnect the STB to the TV directly.
Do a search for "HDMI Receivers". This issue has been discussed quite often.
Also, adaptors have been known to cause issues. See the Digital Home FAQ "DVI/HDMI Information".
Also, the Optoma is not an HD projector, therefore it may not be HDCP compliant.
The following site says it is HDCP compliant, therefore it should work if you go directly from the STB to the projector. Or you can use component video.
(Click on the specifications tab)