i take it was a hdcp handshake issue?
Most likely - or perhaps a bad cable somewhere in the path that you've now been able to skip past. Are you running the video output of the Pioneer at 1080p? That would increase the bandwidth required and could cause a "borderline" cable that worked with a 1080i source to fail to deliver a complete signal. Since we're in the digital domain, there's no "fuzzy" picture as signal strength drops or picture missing one color set: you either get everything, you get some "sparklies" if the signal strength is just a little lower than the display would like, or you get nothing because the signal is too weak or incomplete for the display to decode.
maybe its because its a new pioneer blu ray player with special copyright protection gizmos that mess up with the hdmi to dvi cable?
Nope - there's no way for it to know or care that there's a DVI connector anywhere in the signal path, because it's nothing more than a pair of adapters that match up the different pin configurations. Seriously - going from HDMI to DVI for video is a passive and transparent process. The only thing that happens inside a DVI-to-HDMI adapter or cable is that the wires go to different shaped plugs. The same number of video wires pass through as would exist with DVI-to-DVI (single link) or HDMI-to-HDMI.