on 2 occasions today when going to finish a call by pressing ' End call ' the screen was black. No matter what button i pressed nowt happened, the phone wouldn't even turn off, it was as if it was off but even holding the on button wouldn't bring it to life. So... open back, battery out, close back, Turn on. My ringtone ( stored on card ) was gone when called again and same thing happened when going to End call. repeated process of taking bat. out etc. Since the first time this ' black ' happened I have the info ' damaged SD Card, I might have to re format it. Any idea why this has happened? Am I ok to reformat the SD card without losing anything? What's the worst that can happen or is this quite safe? I use a mac if this is any help.