I have a jailbroken iPhone 4 on iOS 5.1. It had been on 5.0.1 until recently, but I was trying to fix a problem with Nike+iPod, so I upgraded (5.0.1 no longer being signed and all). The problem remains. The problem is that when I go into settings, Nike + iPod, the button to turn it on and off is grayed out. I have tried rebooting, resetting, etc, and the only time that it worked was the brief period when I had 5.1 installed but not yet jailbroken. At that point, I turned it on (and the app installed itself), but once I jailbroke, the on/off toggle grayed out again, and the app crashes every time I start it. Has anyone else experienced this? I just bought the little sensor unit, so I have no experience with the app. I don't know if it's just coincidence that this is happening when I'm jailbroken or if it is the result of being jailbroken (which would seem sort of odd to me, and there does not seem to be a Cydia fix, which I would expect if this were the case). Any help much appreciated!