I have an iPhone 3G running 4.1 jailbreak. As soon as I installed 4.1 it gave me problems, yes theres no more lag but now when I sometimes open certain apps the phone will freeze a bit and then reboot itself. This week it has decided that it does not want to tether with my MacBook Pro. every time the phone makes a tether connection with the mac (USB or Bluetooth) it reboots itself and takes up to 8 minutes to get itself running again. Last week I was tethering just fine. The only thing that I think could have a possible effect is the carrier update the phone asked me to install over the air. Could the be the problem? Thanks guys.