Big Problem :Sony Xperia (P) Lt22i shutting down after inserting a Sim card

Sony Xperia (P) Lt22i shutting down after inserting a Sim card.

What happens is:
– the phone works fine if the sim card is not inserted.
– when the sim card is inserted, the phone asks for the pin (if the card is protected), validates and accepts it, and then, within a very short while, it shuts down. Really it looks like a configuration problem, the running programs detects something is missing and so it shuts down.

i do this mothod but it’s not working :

1.remove sim and start the phone android system settings by dialing *#*#4636#*#* code in phone dial up. phone information and select wdcma only.
4.insert sim and let phone restart and **bleep** soon **bleep** it starts switch to airplane mode before it switches off.
5.repeat step two ,now the settings there will be automatically on ‘unknown’.go to mobile network and select ur sim card network the phone signal will re-appear.