I have owned a Lumix DMC -TZ7 and have taken thousands of photos with it am generally very happy with its performance. However I recently had to have it serviced as photos suddenly, for no obvious reason, started showing blemishes in three areas. These started appearing mid way through a shoot of some countryside scenes. It looked to my inexpert eye as though the sensor had been damaged or burnt out in some way. I can't understand how dust or other material might have entered the camera, particularly mid-way through a shoot during which the camera remained in my hand the whole time. The shoot took place on a calm, sunny day and the air was free from dust. How can I avoid similar problems Thanks!