 Temozolomide and R115777 will both be taken by mouth. Participants in this study will take temozolomide once a day for 7 days every other week Days 1-7 and 15-21. This will be repeated every 28 days 1 course. Patients must not eat for 1 hour before and after taking the drug; drinking water is allowed. All treatment may be given on an outpatient basis. 