Ive had a blackberry curve 8520 since March, and in the past week the buttons havent been working properly on the keypad.. it keeps putting loads of i's in the sentences, then it changed to y. and now most of them arent working. i dont know whats wrong with it, but i took the battery out and put it in the airing cupboard and they worked fine but soon went back to how they were before. now when i put the sim in it says invalid simcard or simcard error? can anyone help me