PPCGeeks - Freezes during call

My phone will freeze during a call. I will still be able to talk to the person and they can hear me, but when I go to hang up I cannot end the call or perform any other function for that matter. This problem appears to only happen if I press the power button during the call to turn off the screen, i.e. I cannot turn the screen back on. I should also add that the problem isn't immediate. For example, If I turn the screen off during a call and then turn it back on ten seconds later for whatever reason everything is fine, but if I turn it off and wait a few minutes and then attempt to turn it back on I will have this problem.

Is anyone familar with this problem?