Inclusion Criteria

Patients may be eligible for this study if they:

• Are HIV-positive.
• Have viral load (amount of HIV in the blood) greater than 500 copies/ml.
• Have received anti-HIV treatment previously with an NNRTI plus an NRTI combination or only NRTIs for greater than 8 weeks and, if not currently on treatment, have been off treatment for 12 weeks or less.
• Failed to keep their viral load low during previous anti-HIV treatment.
• Are at least 18 years of age.
• Agree to use an effective barrier method of birth control.

Exclusion Criteria

Patients will not be eligible for this study if they:

• Have used a protease inhibitor for more than 14 days.
• Have used ddI or d4T for more than 30 days.
• Are pregnant or breast-feeding.
• Have an opportunistic (AIDS-related) infection requiring treatment at the time of enrollment.
• Have, or appear to have, peripheral neuropathy (a painful condition affecting the nervous system) at the time of screening.
• Are at risk for, or have had, pancreatitis (disease of the pancreas).
• Have difficulty absorbing medications.
• Have a cancer, other than Kaposi's sarcoma, that may require systemic treatment.
• Have any medical condition or treatment that may cause a rise in viral load.
• Have any other condition or previous treatment that would interfere with the study.
• Are unable to take drugs by mouth.
• Are receiving or have received recently any of the following drugs: terfenadine, astemizole, cisapride, triazolam, midazolam, ergot alkaloids, amiodarone, bepridil, flecainide, propafenone, quinidine, pimozide, rifampin, and intravenous (IV) pentamidine.
• Are receiving vincristine, thalidomide, foscarnet, or cisplatin or other medications that may cause nerve damage.
• Have received any experimental drug within 30 days prior to treatment.
• Are receiving treatment with testosterone, anabolic steroids, growth hormone, or megestrol acetate, except for certain hormonal problems.