I may have found a solution From what I've seen from my vita it's an update issue This what you do to fix your vita. First make sure your vita isn't charging or plugged in. Then Hold the power button for about 30 seconds. Then you should be in safe mode then choose either restart vita or rebuild data base. You should press restart vita first then it should take you to the the screen lock. After that your vita should be able good to go But don't plug the charger in because your vita will freeze To charge just press shut down and charge it at night or something. Hope this helps you Please spread this around until the next update which should take care of the problem
if freeze after the date ...
I left my PS VITA in the sun for thirty minutes. Then he warmed up and jumped the registration PSN. He went straight to the home screen. Problem solved! Working perfectly!
See this video: http://www.youtube.com/watch?v=VdKpfX8RB1Q