Inclusion Criteria

Patients may be eligible for this study if they:

• Have a viral load of 1000 or more copies/ml within 3 weeks before randomization. Have a CD4 cell count of 50 or more cells/mm3 within 3 weeks prior to randomization.
• Are at least 16 years old (or the minimum age by local requirements).
• Have had more than 16 weeks of therapy with a non-nucleoside reverse transcriptase inhibitor (NNRTI) and/or nucleoside reverse transcriptase inhibitor (NRTI).
• Use effective barrier method of contraception.
• Give written informed consent.
• Are available for follow-up for at least 52 weeks.

Exclusion Criteria

Patients may not be eligible for this study if they:

• Have used a protease inhibitor (PI) treatment for more than 7 days or within 30 days prior to screening.
• Have a newly-diagnosed HIV-related infection or any medical condition requiring relatively short but intense therapy at the time of enrollment.
• Have hepatitis in the 30 days before the study. Patients with long-term hepatitis are eligible if their liver function meets certain requirements.
• Are unable to demonstrate responsiveness to a provided NRTI.
• Have had previous or expect a need for therapy with agents that may cause damage to nerve tissue, the pancreas, the liver, bone marrow, or cells within 3 months of study start.
• Use too much alcohol or drugs to be able to follow the study therapy; or if they use enough to increase the risk of developing pancreatitis or chemical hepatitis.
• Have severe diarrhea within 30 days prior to study entry.
• Are pregnant or breast-feeding.
• Have a history of hemophilia.
• Have history or signs of bilateral peripheral neuropathy.
• Have cardiomyopathy.
• Have certain heart problems.
• Cannot tolerate oral medication.
• Have any other problems that would interfere with the study.