RATIONALE: Sodium stibogluconate may stop the growth of tumor cells by blocking some of the enzymes needed for cell growth. Interferon alfa-2b may interfere with the growth of tumor cells and slow the growth of melanoma and other cancers. Drugs used in chemotherapy, such as cisplatin, vinblastine, and dacarbazine, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Giving sodium stibogluconate and interferon alfa-2b together with combination chemotherapy may kill more tumor cells.