This phase I trial is studying the side effects and best dose of ABT-888 when given in combination with temozolomide in treating young patients with recurrent or refractory CNS tumors. ABT-888 may stop the growth of tumor cells by blocking some of the enzymes needed for cell growth. Drugs used in chemotherapy, such as temozolomide, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Giving ABT-888 together with temozolomide may kill more tumor cells.