How to solve this iPhone 2G problem?

I have an iPhone 2G, and I just update the firmware from 3.0 to 3.1.2 and also I jailbreak it with redsn0w. After rebooting, the iPhone doesn't allow me to go to "Home", and it just allow me to have an emergency call. When I connect it to the computer, iTunes says "The sim card inserted in this iPhone does not appear to be supported", and I've never seen this problem before. So can anyone tell me whay's wrong with this phone and how to deal with it?

Bring it into the store you bought it from they should be able to help you