Sounds like it's just a software hiccup, try doing a factory reset to re-install the OS.
Back up all data to an external source, like an SD card, and power the device off.
Remove the SD card and SIM card.
Press and hold volume up + home, press power repeatedly until phone vibrates.
Wait until Android logo is visible, then release all buttons.
Select Wipe Data/Factory Reset using the volume keys, and press power to confirm.
Select YES, and press power to confirm.
After the reset, select the option to reboot and press power.
If the issue still persists after this, take the phone into one of your carriers stores/kiosks and ask for assistance.