My iPhone 4 likes to lock up on me when closing apps in multitasking and it'll just sit there with the multitasking screen up not allowing me to do anything. I usually have to wait 45secs-2mins for it to unfreeze or just do a reset with the home/lock button. Does this happen to anyway else? Any suggestions on what I should do? It has done this on 4.0, 4.1, and now 4.2 no changes.