Poor color depth in menus and programming

Today I noticed that both DirecTV programming and the Tivo menus have lower color depth than before. Faces in programming look slightly cartoonish. The ball-shaped bullets in "Now Playing" have obvious, coarse dithering. It's like viewing a webpage on a PC with 256 colors.

I have a Hughes Series 2 model HDVR2, running software version 6.3e-01-2-151.

I have not touched the cables in several weeks. I am using an S-Video cable from the Tivo unit to an off-brand digital 720p television.

I tried checking the TV by playing a DVD and the color depth looks normal there, although the DVD player is going in through HDMI and not S-Video. I've reviewed the video settings for the television and I don't see anything that looks like it affects color depth.

Suggestions, corroborating experiences, ???

thank you very much.