When I got my HTC Desire Z about six weeks ago, the camera worked fine - I could take photos, upload them to facebook, and come back later and view photos I have taken previously. Now however when I try to view photos I have taken earlier - eg yesterday, or two weeks ago - some of the pictures are missing. Other pictures- quite a few in fact - won't open and when I scroll through, just show a blank screen with a little square in the middle with what looks like a dot and two lines, and an exclamation mark next to it. I'm guessing these photos have been corrupted in some way - does anyone know why this might have happened, what I can do to stop it from happening again, and if there is any way to restore the missing photos? Thanks!