Phase I trial to study the effectiveness of rebeccamycin analog and cisplatin with or without filgrastim in treating patients who have advanced cancer. Drugs used in chemotherapy use different ways to stop tumor cells from dividing so they stop growing or die. Combining more than one drug may kill more tumor cells. Colony-stimulating factors such as filgrastim may increase the number of immune cells found in bone marrow or peripheral blood and may help a person's immune system recover from the side effects of chemotherapy.