Spinning wheel after unlock

I'm able to restart my phone and get to the lock screen. The wallpaper shows up and I can even receive calls after a restart. I can access the unlock screen and enter my passcode. After that, I get the black spinning wheel for a few minutes until the phone reboots again. I can't connect to itunes because I can't tell the phone it's OK to connect because it's in this state where it locks up as soon as I enter my passcode. What can I do?