RATIONALE: Bortezomib may stop the growth of cancer cells by blocking some of the enzymes needed for cell growth and by blocking blood flow to the cancer. Drugs used in chemotherapy, such as dexamethasone, ifosfamide, carboplatin, and etoposide, work in different ways to stop the growth of cancer cells, either by killing the cells or by stopping them from dividing. Monoclonal antibodies, such as rituximab, can block cancer growth in different ways. Some block the ability of cancer cells to grow and spread. Others find cancer cells and help kill them or carry cancer-killing substances to them. It is not yet known whether giving bortezomib together with combination chemotherapy is more effective with or without rituximab in treating AIDS-related non-Hodgkin lymphoma.