Hi
I've had the same problem on three different handsets the last of which went back to Samsung under warranty. They so called repaired it and returned it but the problem is still there. If I have the " Alternative Frequency " option ticked in the settings of the radio, the radio crashes after a few seconds which in turn forces a restart of the phone. However if I don't have the option ticked the radio works fine. I've tried to speak to someone at Samsung who has technical knowledge but just come up against a brick wall. Perhaps we need more people to check this issue and report it to Samsung then they may do something about it.
Cheers