C500 crashing

[Guest tomsmart]

Can someone please help! Last night my C500's battery ran out because I forgot to plug it in. I have now fully recharged it and when switched on it looks perfectly normal with the home screen showing. However, if I press any key at all it goes to the sunset screen for a second and then goes black (with, incidentally, the bluetooth blue light still flashing). It then fails to respond to anything except removing and replacing the battery. When I do this, it boots up immediately without me having to press the power button. Once it has booted up I am back to the original situation where it looks fine but will crash on any key press.

I have tried many things including: removing the battery for some time; doing the soft reset; and doing the hard reset (the one that involves pressing both soft keys simultaneously). Incidentally, when the phone is booted up, it shows incoming calls and sms messages normally, but of course I cannot answer them without it crashing.

ANY IDEAS!? Increasingly desperate.

Thank you.

T