42" Polaroid LCD loses most colors

Try replacing your lcd controller. It's the board that actually makes the screen display the picture. Usually you will see the colors getting a little screwy and then the longer you have the tv on the hotter it gets and the worse it gets. I had one that started to look silvery then got worse as it got warmer. For lack of better ways to describe it, it was like you were watching tv on a crazy acid trip. Once you change the controller it should be ok. If that doesn't work 99% chance it's a bad lcd panel. I've seen about 6 of those all with similar issues as you have, they were all brand new tv's and all Sharp Aquos.