Navigation Touchscreen Problem

[jlgone]

The Nav screen in my 2004 GX470 GPS has a problem. It periodically (every 10-20 minutes) zooms out onelevel without any touching of the screen, so after a day of driving I can see all of north america! I can go to the set up menu and zoom back in by using the recalibration controls, but when I try try to do it from the main screen I can't get the "plus" button to function. It seems the symbols on the screen don't line up with where you are touching. It seems like there are two problems - uncontrolled unwanted zooming, and misalignment of the screen control images with the touch points.

The screen has no physical damage. On screens with jusy a few controls, the screen operates properly, but when I need to slecet a button in the extreme lower left corner (e.g., the + button for map zoom) it selects the botton to the right. It seems like the touchscreen zones has been shifted to the left by an inch. I also have trouble typing in the address letters I want sometimes (again, misaligned or totally random letter selected when I touch the screen). Some screens work fine (the "I agree" one and others with only a few buttons. The radio controls usually work, but sometimes it selects the wrong station as well.

Is this a problem with the screen or the computer/program? Has anyone experience this before - I searched but couldn't find this problem on the forum. I don't want to take it to the dealer and get charged thousands for a new system if the computer or a softwate update would fix this. It seems like I could get a used screen if that is the problem.

Thanks for your help!

PS - it is using DVD version 3.1