I've noticed that when I send a text and then lock the phone (button on top) it freezes when you try replying to that text. You can also try it out by sending yourself a text, push the lock button at the top and when you get your reply back, unlock your phone and try replying and see what happens. This is gonna be my final straw on exchanging the phone for a new one. Below is the message I'm getting when it finally unfreezes. "Sorry! Activity Messaging (in application Messaging) is not responding." You get 2 choices to "Force close or Wait."
Can someone please try this and see if this happens to you. Thanks very much!!!!