RATIONALE: Drugs used in chemotherapy, such as arsenic trioxide and dexamethasone, work in different ways to stop the growth of cancer cells, either by killing the cells or by stopping them from dividing. Ascorbic acid may help arsenic trioxide work better by making cancer cells more sensitive to the drug. Bortezomib may stop the growth of cancer cells by blocking some of the enzymes needed for cell growth. Thalidomide may stop the growth of cancer cells by stopping blood flow to the cancer. Giving arsenic trioxide and ascorbic acid together with bortezomib, thalidomide, and dexamethasone may stop the growth of and kill more cancer cells.