2004 E53 w/ Nav - Pixels turning gray

[Dupersenior]

I have a 2004 4.4i with the factory nav system. I got it about a year ago, and the nav screen was perfectly fine at that point. Now, splotches of pixels are turning gray (but still lit - not black). The splotches seem to be growing slowly, and they're showing up in more spots on the screen. It seems to have started when the weather starter getting warmer. Anybody know what causes this, and if I can reverse it or prevent it from getting worse?

Thanks!