Patients are randomized into 2 cohorts, with Cohort 2 receiving a higher dosage than Cohort 1. Patients in each cohort receive either (+)-calanolide A or a placebo for 14 days, followed by a 14-day follow-up period. Following study treatment, patients may elect to receive an open-label, 6-month course of anti-HIV drugs to be selected by and administered under the care of the patient's physician.