My iPhone 4 (32G) keeps shutting off.

For the last 2 weeks, my iphone keeps shutting off. The battery is not dead and when I plug into a power source I get the apple logo. Sometimes the date shows as 12/31 at 6:00 and is searching for service.

I have tried hard resets and they rarely do much. A few days ago it seemed to work and I went a few days with no issue but today same thing.

I have cleared the Safari cookies and cache and that didnt seem to do anything. I am clueless on where to go from here.

I am outside my warranty fyi.

Any help is much appreciated.