 This phase I trial is studying the side effects and best dose of decitabine and FR901228 in treating patients with relapsed or refractory leukemia, myelodysplastic syndromes or myeloproliferative disorders. Drugs used in chemotherapy, such as decitabine and FR901228, work in different ways to stop the growth of cancer cells, either by killing the cells or by stopping them from dividing. FR901228 may also stop the growth of cancer cells by blocking some of the enzymes needed for cell growth and by blocking blood flow to the cancer. Giving decitabine together with FR901228 may kill more cancer cells. 