Same problem for me too "my phone gets switched off when i am talking on the phone for more than 20 min" i went to samsung care for this problem, first time they said this could be a software problem and they flashed a new firmware and gave it to me the problem was not solved then i went the second time this time they said that it was a mother board problem and they changed it gave it to me yesterday i.e on 17.12.11 now still i have the same problem. i dont know what to do now i think i will take it tomorrow again