Onkyo 609 help

Can anyone help with an issue with the onkyo 609 

When I connect my blu-ray and output to audio and projector,everything works but when I connect the cable box nothing outputs.

But if I unplug the hdmi cable from the projector I get sound from the speakers but as expected no video, when I connect the hdmi again the everything stops working!

is there anything obvious in have not done re the setup as I thought hdmi should just pass thru both audio and vido

Cheers