Game apps that leak memory can cause this to happen: you open the app and it begins to load but then closes and takes you back out to your home screen. This is the iPhone's way of handling crashes.
- I have found that after you reach this point, no other apps will open - they all do the same - except for the default built-in iPhone apps like phone, text, Safari, etc.
- Also I have found that the issue goes away most of the time if you simply soft-reset the phone. This dumps the RAM, just like rebooting your desktop computer.
- Sometimes though, in a stubborn case, this doesn't fix it. Prior to just now, I thought the only other way to fix it was to sync the phone in iTunes on my computer. This is an easy fix if I was home, but rarely does it seem to happen at such a convenient time.
- So, I did some searching and found that some people were fixing it by removing and reinstalling apps. All I did was hit the store and found I had 1 app update. I updated it which triggered my phone to authorize at the iTunes store. The app updated and opened. Now suddenly, magically, other apps open normally again too!