Here is the real answer. This applies to ALL Android devices!!
Your phone has too many apps installed or running. When the Android OS runs out of memory, the OS becomes unstable. Android then reboots itself to free up memory. If you have too many 'active' applications or services running, when the system reboots, it will again, run out of memory, and reboot again, in an endless loop.
There are two solutions. 1. Uninstall applications until the Android OS has enough free RAM to run stably. Install a automatic memory manager. 2. Shut the device down and restart it, holding the volume up button and power button until the 'Service' menu appears, then select the restore to factory installation option. This will restore the device to 'Factory' settings and wipe all user apps and data. Install a automatic memory manager.
Warning! You will lose all applications and data if you do number 2 option.
But, either one will give your device it's sanity back. Then you can be more careful about installing too many apps. Remember, you only use 2 or 3 apps all of the time anyway. Do you really need all of those junk apps????