Xperia Z3 :: Apps Crashing / Random Rebooting

I recently bought a new Sony Xperia Z3. The problems I am experiencing are that all sony default apps crashing and some other apps aswell. Apps that have crashed are; the contacts app, the messenger app (not facebook), the homescreen app, the album app, the walkman and the movies app.

When they crash I get a message saying Unfortunately "app name", has stopped. The only way to make the app working again is to reset the phone. This happens quite often which is surprising since the phone is new and its a flagship device.
 
The second problem I am experiencing is the phone randomly resetting itself, this happens about once per day. I believe the reason for the random resets are the crashing apps. I think that because when I was using my phone all apps suddently crashen, then the phone just reset itself twice before it was usable again.