Green 'tearing' on HD projector when image contains pure black or pure white
I installed a Mitsubishi FD630U projector in to one of our halls over the holiday, and have it connected to a desktop's second monitor output. The second monitor output is DisplayPort, so I've used a DisplayPort to HDMI cable to connect it to the projector's HDMI port.
This works fine, except in one scenario: whenever there is a significant amount (anything more than about 15%) of pure black or pure white on the screen, a green horizontal 'tearing' effect appears on that part of the image, and the rest of the image also experiences some interference (not green, more like intermittent missing pixels). This causes a problem with PowerPoint, unless you set the background to slightly off-whiter (or slightly off-black). In extreme cases, the projector will actually lose sync entirely, then flick back a second later.
The rest of the time, the image is perfect. This happens regardless of image resolution or whether the computer is in duplicate or extended. I've got different cabling coming in on Monday to test, and my next step will be to try a different computer, but am wondering in the meantime if anyone has seen this sort of thing before and knows what might be causing it?