Additional Study Information: The purpose of this study is to evaluate a new experimental (investigational) oral combination hormone drug product containing estradiol (a form of the estrogen) and progesterone (a female hormone that regulates the inner lining of the uterus called the endometrium) for postmenopausal women who have hot flushes. The estradiol and progesterone used in this study are similar to the natural estrogen and progesterone produced by the ovaries prior to menopause. This study will determine the safety of this combination drug and if it works in treating hot flushes (also called "hot flashes") and managing endometrial hyperplasia (the excessive growth of cells in the lining of the uterus).