Some patients taking anti-HIV drugs develop hyperlactatemia. Hyperlactatemia is a condition in which lactate (a natural substance normally present in the body) levels are too high. Too much lactate in the body can lead to serious health problems. When patients suffer from hyperlactatemia while taking anti-HIV drugs, most doctors temporarily stop the drugs. Patients then restart the anti-HIV drugs when their lactate levels return to normal. If patients restart the same drugs they were taking when they developed hyperlactatemia, there is a risk that they may develop high lactate levels again. This study wants to find out if taking antioxidants (substances that reduce tissue damage due to oxygen radicals) and certain B vitamins may help prevent patients from developing hyperlactatemia when they restart the same anti-HIV drugs.