A Study of Increased Lactic Acid and Abnormal Fat Distribution in HIV-Positive Patients

Inclusion Criteria Patients may be eligible for this study if they: * Are HIV-positive. * Are at least 18 years old. * Agree not to have intercourse 2 weeks before, during, and 2 weeks after study or agree to use effective methods of birth control. * Have had HIV-1 RNA levels less than 400 copies/ml on the 2 most recent measurements. * Have at least 1 of the following situations: * (a) at least 1 of the following: (1) decrease in facial fat, (2) decrease in fat in lower limbs, or (3) decrease in fat in buttocks area; or * (b) an increase in lactate level greater than 2.2 mmol/L at the screening visit plus at least 1 of the following: (1) decrease in facial fat, (2) decrease in fat in lower limbs, or (3) decrease in fat in the buttocks area; or * (c) an increase in lactate level greater than 2.2 mmol/L at screening visit plus at least 2 of the following: (1) shortness of breath, (2) weakness, (3) fast heartbeat, (4) recent weight loss (10 lbs. within the past 2 months), (5) pain and/or bloating in the abdomen, (6) nausea and/or vomiting and/or lack of appetite; or * (d) lactate level greater than 3.2 mmol/L at the screening visit. * Are able to read at a sixth-grade level. * Have taken d4T consistently for the 6 months before entering study. Exclusion Criteria Patients will not be eligible for this study if they: * Have diabetes or kidney failure. * Have any condition that makes them unable to participate in this study. * Are unable to take medications by mouth. * Have serious medical conditions, such as congestive heart failure or other heart disease, which would affect the safety of the patient. * Are taking or have taken abacavir plus Retrovir or Combivir. * Are pregnant or breast-feeding. * Are enrolled in other clinical studies. * Have had a reaction to or are unable to take abacavir and have taken Retrovir in the past. * Have taken hydroxyurea within the past 3 days or plan to take this drug during the study. * Have had chemotherapy or radiation therapy within 4 weeks prior to screening visit (except for local treatment for Kaposi's sarcoma) or plan to have such treatment during the study. * Have taken drugs that affect the immune system, such as systemic corticosteroids, interleukins, vaccines, or interferons, within 4 weeks prior to the screening visit. * Have had an HIV vaccine within 3 months of the screening visit. * Have taken recombinant Human Growth Hormone (r-hGH), megestrol acetate, medicines containing oxandrolone, oxymetholone, nandrolone, DHEA, or other testosterone derivatives, or glucocorticoids or other systemic steroids (except inhaled and topical steroids) in the last 4 months or plan to take these drugs during the study.