Hi, I have an iPhone 3GS that had been recently replaced by Apple. Had the old bootrom, jailbroken and unlocked with Spirit/ultrasn0w on 3.1.3. My iPhone worked without a hitch. However, ever since upgrading iOS 4 (jailbroken via Spirit2pwn and Pwnagetool), my 3GS, my iPhone randomly reboots, especially during calls that last more than 10 minutes. So I restored to stock iOS 4 and used my friend's AT&T sim to test if this was issue with jailbreaking, but my 3GS continues to reboot itself randomly. So I downgraded back to 3.1.3 using Saurik's servers and my phone no longer reboots. I was wondering if any other 3GS owners out there are experiencing the same issues as well.