AT&T says in the article I linked that if the restart does not work to toggle airplane mode. Both will force the phone to resync with the network. Your switching to automatic did the same thing but both the restart and toggling airplane mode are easier than having users turn their clock to manual and then to automatic.
Mine is always on automatic but if you are on AT&T that was probably a coincidence.
My phone would not call out or receive calls after and update. To fix my problem I turned my clock from manual to automatic and it let me make and recieve calls....
