ARM I: Within 5 weeks after completion of chemoradiation, patients receive temozolomide orally (PO) on days 1-5. Treatment repeats every 28 days for up to 6 courses in the absence of disease progression or unacceptable toxicity. Patients also receive ipilimumab intravenously (IV) over 90 minutes once every 4 weeks for 4 courses and then beginning 3 months after course 4 once every 3 months for 4 courses in the absence unacceptable toxicity.