PRIMARY OBJECTIVES: I. To evaluate the 6-month progression-free survival in patients with recurrent or progressive high grade gliomas treated with ritonavir and lopinavir. SECONDARY OBJECTIVES: I. To evaluate the toxicity of ritonavir and lopinavir in this patient population. OUTLINE: Patients receive oral ritonavir and lopinavir twice daily in the absence of disease progression or unacceptable toxicity. After completion of study therapy, patients are followed periodically.