LCD losing resolution?

When I bought my new TV I gave my mom a Westinghouse 37" LCD that I was using. It's a Westinghouse LVM-37w1. It's been fine up until now. Then suddenly after a little while the picture changes. I can't describe it very well except to say that it looks like when you change the color setting on a PC from say 256 colors to 128. The way colors seem to become more general. Sorry for the lack of proper terminology.

It doesn't last very long but it's starting to happen more frequently. It comes and goes at random. No set reason that I've found. And no set time limit. While it's happening I've tried adjusting the brightness, contrast, hue, sharpness, etc. and nothing makes a difference.

Thanks in advance for any and all help.