Additional Study Information: The purpose of this study is to determine if Nexavar (sorafenib), the study medication, is effective in preventing cancer recurrence in high risk patients following liver transplantation. The purpose of this study is to determine if sorafenib is a safe and effective treatment option for preventing the recurrence of liver cancer in high risk subjects following liver transplantation. Study participants will be randomly assigned to a group that either receives sorafenib or a placebo (a pill that doesnt have any drugs or medicine). Every study visit will require a blood draw and a physical examination.