It seems something in your phone settings has become corrupt. I would recommend performing a hard reset to clear this up. The instructions to performing the reset are listed below:
Performing a factory reset via settings
The most convenient way to do a factory reset is via the phone settings.
Press HOME
> MENU,
then tap Settings.
Scroll down the screen,
and then tap Privacy
> Factory data reset.
On the Factory data reset screen,
tap Reset phone,
and then tap Erase everything.
Once you have done this it should resolve your issue. Hope this helps.
