 3. At least 3 consecutive months experience taking antiretrovirals ARVs from each of the classes of nucleoside reverse transcriptase inhibitorsNRTIs, non-nucleoside reverse transcriptase inhibitorsNNRTIs, and protease inhibitors PIs at some point in treatment history,with at least 2 protease inhibitor PI-based regimens, one of which must be the current regimen, and current protease inhibitor PI-based antiretroviral ARV medication regimen for at least 3 months prior to randomization. 