Here is something that will fix a huge amount of the common issues you might encounter with the iPhone. Just restart it. Like if it is sluggish to respond, or things are freezing, etc. Its running OSX so it makes sense when you think about it in terms of running any OS. It just doesn't occur to most people in terms of a cell phone.
Here's what I did and it worked for me.
To restart the iPhone, press and hold both the sleep/wake button (on top of the iPhone) and the Home button (centered below the screen) for a few seconds.
When you see the Apple logo, you can let go and the iPhone will start back up.
You should probably do this every now and then just to keep the thing running smoothly.
