after trying probably 50 or 60 times to connect my bluetooth headset to my iphone 4s I've found a fix. Start your idevice in safe mode by using sbsettings/power/start in safe mode. once your idevice restarts go settings/bluetooth then rescan for your bluetooth device in the normal way once detected enter your code then close the settings and on the status bar will be (exit safe mode) restart your device by tapping on (exit safe mode ) and voila you have a fully functioning bluetooth connection