Yeah, its probably the port.. maybe not the port or pins themselves but caps or traces on the mb where the rgb port is..
INdy mk2 looks good for you because it comes straight off the chip bypassing the lines for the video port.
Wow looks amazing! How many colors is that? I'll have to get my 1200 back online and try the new modes.
btw how are you guys embedding these images. I tried with Picasa embeded link and it doesnt work here?