This is a study of the drug perifosine that consists of 2 parts. The first part of this study was designed to determine the highest dose of perifosine that can be administered to people every week without severe or prolonged nausea, vomiting and diarrhea. This study started with patients taking 900 mg/week and went up to 1800 mg/week. Part I of this study is completed. The MTD had been determined and incorporated in Part II.