Clinicians are increasingly confronted with HIV-positive children who have failed all available antiretroviral therapies and have few viable treatment options. Virologic failure in these patients may be a result of antiretroviral resistance, likely a result of poor adherence to the treatment regimen or inadequate dosing. This study is designed to achieve adherence through observation of drug administration for the first 8 weeks of the study and to further overcome resistance by intensive, high-dose, multi-drug therapy. Treatment with more than 4 drugs has not been studied formally in children, but pediatricians caring for children with AIDS have used such strategies off study with success. Dose intensification may also aid in overcoming resistance; therefore, in this trial, d4T, 3TC, and NFV are administered at up to twice their standard doses. Given the limited therapeutic options available to HIV-positive children with poor prognoses, high-dose, multi-drug therapy merits study. [AS PER AMENDMENT 01/07/00: Pancreatitis, which may be fatal in some cases, has occurred during therapy with ddI. The risk of pancreatitis may be increased when ddI is used in combination with HU. ACTG A5025, a study that had a d4T/ddI/HU arm, was terminated because of significant toxicity concerns related to the HU-containing arm. Patients enrolled in ACTG P1007 may be at increased risk of developing pancreatitis given their advanced disease state and the use of multiple drugs including HU. The study had been amended to address these concerns.] [AS PER AMENDMENT 12/19/01: HU has been removed from the drug regimen.]