Salvage Treatment, Resistance Testing, and Withdrawal of Anti-HIV Drugs for HIV Patients Failing Current Anti-HIV Treatment

Inclusion Criteria Patients may be eligible for this study if they: * Are HIV-infected. * Are likely to have drug-resistant HIV from having taken all types of anti-HIV drugs (protease inhibitors \[PIs\], nucleoside reverse transcriptase inhibitors \[NRTIs\], and nonnucleoside reverse transcriptase inhibitors \[NNRTIs\]), and having failed treatment prior to the current treatment for reasons other than toxicity. * Are currently receiving anti-HIV treatment with at least 3 drugs. Low doses of ritonavir (100 to 200 mg twice daily) taken with 1 other PI is counted as a single PI. * Are currently failing treatment due to a high viral load (amount of HIV in the blood). * Have had a new anti-HIV drug combination selected. * Are at least 18 years old. * This study has been changed to remove CD4 counts as an inclusion criterion. In the previous version of the protocol, patients were required to have a CD4 count of 150 cells/ml or more within 42 days prior to study entry. Exclusion Criteria Patients will not be eligible for this study if they: * Have stopped treatment for more than 4 weeks in the past 6 months. * Are pregnant or breast-feeding. * Have cancer that requires systemic treatment or radiation. * Have received the following medications affecting the immune system within 14 days before entry: erythropoietin; Granulocyte Colony Stimulating Factor (G-CSF), including Granulocyte Macrophage Colony Stimulating Factors (GM-CSF); interleukins; or therapeutic HIV vaccines.