iPhone freezes when Wifi connection drops

Whenever the iPhone drops a Wifi connection, the operating system freezes in 10-seconds increments. I can tell, because when I'm on the page where the clock is, the second hand moves in 10-second increments. In other words, it "unfreezes" for a fraction of a second every 10 seconds.

Sometimes the Wifi reconnects and the problem is solved. But often, this goes on and on an on, and I can only solve it by restarting the phone. This is a problem, too, because the power button has to be pressed for a longer time than the fraction of the second the phone unfreezes.

If the phone stops freezing up without restarting, the Wifi refuses to turn on for a while.