Falling code / application code
Several people have a problem with the iphone in a reboot mode or application code keeps scrolling on the screen after the apple logo disappears when iphone is turned on.

I had the same problem. here is what I did:
1. put the iphone in restore mode. (held down the power button until triangle or connect to itunes appears - do not let go of the power button.
2. keep holding the power button and connect to itunes.
3. itunes said phone needed to be restored.
4. restored iphone with original version that phone was shipped with.
Note: you should still be holding the power on button
5. once the restore completes release the power on button and restart the phone.

PS you could try releasing the power on button once the restore starts. If phone goes back to rebooting or displaying application code you will have to hold the power on button until the restore completes

Hope this helps someone