Phone Keeps Freezing During Calls!

[NVash]

So I get a phone call and I answer it. I get a txt shortly thereafter and I hit the Back button to go back to the menu to see the txt. If I do it early enough it might just work. Sometimes, actually most times, it just does nothing then gives me an Error message that the Activity Phone is not responding with an option for Force Close or Wait. Well, I usually Force Close but that ends the convo. Recently I learned to Wait but apparently after awhile that will force the app to close and I lose the convo then as well.

Is this just a problem with my phone or do other people have this? And also, how can I remedy it?