Picture flashes on for 2 secs. then turns off

Are you saying that the Cogeco box switches off, or the TV switches off? Which one?

What happens if you bypass the receiver and go straight to the TV?

If the cable box works fine to your tv through the HDMI-DVI connection then is the same issue I had when I connected using the DVI output to the hdmi connection on my receiver (with an HDMI-DVI connector). It appears to be the handshake between the cable box and tv through HDMI. I just went and bought a different receiver (I had bought a new one so just returned what I bought). The new one I bought converted everything to HDMI so I just run component cables from the cable box and the receiver outputs everything to HDMI. That might not be a solution for you.

What you can try is the order of how you turn things on. I read that solution somewhere but it did not work for me, that is why I switched the receiver.

Neither the box or the receiver or the tv turns off,it just doesn't show a picture. After further investigation with a dvi to hdmi it's not sending an audio signal anyway so going from the cogeco box to the tv with a dvi to hdmi cable and an optical to the Pioneer will be my only option