Recording Problem - Iphone 5, IOS 7

Hi Guys, I have a problem with my native audio recorder from Iphone 5. It's stops recording after aprox. 1 hour, and after, I can't even open the file. It happens all the time.

I'm very angry because I'v recorded an important conference.

Anyone has a solution? I'v reseted, hard reseted and other stuff.

It's not a GB problem!

Please!!