Many users of the Pantech phones have been experiencing the same thing. There are a lot of default in this phone. I would suggest you to return it to Pantech and try to get a software upgrade (if there is!). Although, I would recommend you NOT to use it. Even if the Pantech exchange it for a new one, the same problem will happened in a day or two.

The phone is waterdamaged. there is no way to fix it except for replacing it.