If your source is plugged into the HDMI-2 input, try to plug it into HDMI-1.
I know this sounds far-fetched and perhaps even strange to some, but I've had a similar issue when I try to play YCbCr-material on HDMI-2, apparently it has to do with the fact that input 1 is HDCP 2.2 and Input 2 is only HDCP 1.4. For example, my Bluray player is plugged into HDMI-1 and plays YCbCr without problems, and my PS3 is plugged into HDMI-2, but the PS3 absolutely MUST put out RGB and not YCbCr, or else my projector will do exactly as you describe - go blank and be unresponsive and has to be unplugged. So try looking into this.
That said, I would start thinking about lamp replacement by now if I were you.
My Home Theater setup:
Picture: Benq W2000 (HT3050) // 130" DIY AT-screen // Sony UHP-H1 // PS3
Sound: Pioneer VSX-AX2AV (7.1) // Infinity Beta 50/C360/ES250, Mission 737R, Dynavoice Thunder T-12 // Sinus Live BassPump III