Blackberry bold 9900 screen keeps switching off. need help?

stephen Asked: Blackberry bold 9900 screen keeps switching off. need help?

i am using an orange micro sim card in a sim card holder, the sim card was originally with an iPhone but i rang orange and they sorted things out. Previously, my camera said to 'close applications' before i could use it- and when i did so nothing changed. so i updated to the newest software and the camera works- but the screen keeps unexpectedly turning off on me, sometimes every second after coming off, I've tried taking the battery out, and everything. please can somebody give me some help. the screen has only started doing this since i updated the software.