IPHONE 3Gs is stuck in activation mode after updating to IOS5

I updated my 3GS to IOS5 and it is stuck in activation mode and I keep getting 'there is no sim card that you are trying to activate"or the server is not reponding please try again....it has been 4 days now!I am using the same original sim card the Phone came with plus it has been factory unlock by my carrier Orange for a few months now,I do not understand why???? Can anyone help?