I'm not fully aware how an LCD panel works but I do now it is a liquid and if it is damaged it could leak...I wish Icalo was still here as he would be the one perso who could answer this.
LCD can develop "stuck pixcles" but not usually in that manor.
Yes, the purple text is the "memory" of the menu that was there. I took the photo immediately after moving away from the menu. This memory images occurs on all moving images on the display. On a solid screen you can see the marks moving like a liquid almost. I live in an extremely humid place and usually use the projector in an air conditioned room. I want to think it is just condensation but it doesn't go away, even after several hours of use.
Ahhh, I think I understand now. It's not every image that burns-in, it's just the same menu image that appears no matter what else is being displayed. We may need to wait for someone to chime in who's more familiar with projectors, but it's my educated guess the menu was left on for a very long time (hours). I searched a few forums as well as googled a few articles, and it seems it IS possible for an LCD projector to develop what's called image persistence. You might want to try the link in Post #2 here and see if that helps.
While contemplating your projector's issue another time, I came across some good advice in this thread here that may work for you, too: take a picture of the the displayed image and send it to your projector's manufacturer. They may be able to diagnose it from afar.
My friend had something similar happen on an LCD TV. It turned out to be something in the video processor. In my mind, the original question doesn't seem to fit the description. In the case of high humidity, I would suspect shorted connections, or pcb before moisture in the lens. Just .02 more.