I have an iphone 3G and it used to be with 3.1.3 and jailbroken. I was still reading about how to do the upgrade and keep my jailbreak when my boyfriend decided to update my iphone on itunes. So now i have 4.0.1 and no jailbreak. I tried using pwnage tool and selected the ispw. but it says its not correct. Im guessing something must of gotten messed up with the upgrade.
First thing... Tell your boyfriend to keep his hands off your iPhone... LOL
Second... Downgrade to 3.1.3 FW then re-JB.
Third... Tell your boyfriend to KEEP his hands OFF your iPhone...LOL