Patients will be hospitalized 1 to 2 days each for the first and second doses of docetaxel to allow for frequent blood draws to measure blood levels of the drug. Ketoconazole will be started about 2 weeks after the first dose of docetaxel and the second dose of docetaxel will be given 2 days after that. In order to determine the maximum tolerated dose of docetaxel, the first few patients in the study will be given a low dose of the drug, and subsequent patients will get increasingly higher doses until unacceptable side effects occur. Because prostate cancer cells may grow if exposed to testosterone, patients may have to have their testosterone production suppressed either surgically (removal of the testicles) or medically with an injection of leuprolide or goserelin, which are luteinizing hormone-release hormone agonists that reduce the amount of testosterone.