Patients receive AL-721 twice daily. The first dose is taken on an empty stomach 1 hour before a fat-free breakfast, with specific instructions given on foods that are allowed; the second dose is taken at least 3 hours after the evening meal. No snacks are permitted after the evening meal or after the evening dose of study medication. The study is scheduled to last for 16 weeks of treatment and 4 weeks of follow-up. Throughout the study, frequent blood samples will be taken from an arm vein. The blood samples are studied to evaluate any changes in the patient's immune system, any toxic effects that might be detected in the blood, and any changes in the presence of the HIV in the blood.