I have had my iPhone 4 since June. Soon after I got it (like three weeks), my iPhone was downloading an app and when the screen went black to lock..the iPhone would not respond to any input. All I saw was a black screen and it wouldn't respond whenever it was plugged into my computer. Luckily someone I knew told me about holding the home button and the lock button at the same time, and the iPhone reset itself. About two weeks ago, it did it again. I think its just something with the apps running in the background and I try to close them out anytime I'm not going to use them for a while. Does any one know why this occurs? Is it a glitch with my phone or in general iOS 5?