I have my third replacement of treo600 because of white blotch/spot/discoloration on the treo600. I have never drop it nor anything has drop on it. Finally, i found out that the cause is my magnetic casing. whenever the unit is pressed by its casing, the magnet presses on the LCD and few days later the white spot appear.

Just want to share for those who have the same experience. It might be due to the casing.

Now , i am using velcro as the lock of the casing and so far no problem with the screen.

My two cents.