My iphone 3gs was restarted every two seconds(It is jail broken already). So i try to restore my iphone using itune recovery mode. After clicking on restore, it is try to upgrade ios 5.0 to latest ios5.1. At the end of the installation it says, "the iphone could not to be restored. An unknown error was occured(-1)".

What does it mean? How to I get back my phone normal? Please help, I also tried different operation system.