 Vicriviroc vye-kri-VYE-rock is an investigational drug not yet approved by Government Regulatory Authorities for commercial use that belongs to a new class of drugs, called CCR5 receptor blockers. This group of drugs blocks one of the ways HIV enters T-cells the cells that fight infection. Previous studies in HIV treatment-experienced patients have shown that vicriviroc is safe and effective. The purpose of this study is to determine the effect of vicriviroc on HIV RNA levels in cerebrospinal fluid CSF. 