I don't get an error. The PDF saves and opens just fine, and all the info is there except it is in greyscale, with only one of the lines in color - the yellow (NRQW) line.
However you are correct, in that the viewer is capable of more colors. It displays this just fine:
http://www.wmata.com/metrorail/colormap.pdf
Has anyone found a working NYC subway pdf, or does anyone have a better idea on how to keep a handy reference copy on their Treo? Google Maps for Mobile doesn't yet support subway stops, and Windows Live Search is very spotty in its coverage.
Thanks.