The gray you describe is not how the picture problems, for those that experience it, are usually described.
Normally the sympton can be of a grainy picture overall, some have it coming through a standard aerial connection and others through the scart inputs. The overall opinion is that the latest firmware revision solved this.
Just to be sure, when did you last update? The last release of 098 had the same filename as the previous. Good ol' Liteon.
If it is definitely a Graying of colors then it not an issue I've come across before.
Have tried a different yellow connection lead, it is possible that your current one has a poor solder.
Finally, until they update my 080 firmware I use the front AV connections where the picture quality is much better.