This pilot phase II trial is studying the side effects and best dose of erlotinib when given with temozolomide and radiation therapy and to see how well they work in treating patients with glioblastoma multiforme or other brain tumors. Radiation therapy uses high-energy x-rays to damage tumor cells. Erlotinib may interfere with the growth of tumor cells, slow the growth of the tumor, and make the tumor cells more sensitive to radiation therapy. Drugs used in chemotherapy, such as temozolomide, work in different ways to stop tumor cells from dividing so they stop growing or die. Combining erlotinib and temozolomide with radiation therapy may kill more tumor cells.