This study will test the safety, side effects and anti-HIV activity of different doses of capravirine in children and adolescents with HIV infection. Capravirine belongs to a class of drugs called non-nucleoside reverse transcriptase inhibitors (NNRTIs), which prevent the virus from replicating (making more copies of itself). Other NNRTIs are nevirapine, delavirdine and efavirenz.