Since Pro Tools|HD supports more voices, Digidesign had to expand the number of colors we used -- with Pro Tools|24 Mix systems, there were 64 voices so you had 64 colors. Pro Tools|HD supports 128*, so we had to double the number of colors.As a workaround, you may alter the color of your audio tracks by manually setting the voice for your preferred color (instead of using "Auto Voicing").