After at least 6 patients in Stage A have completed at least 2 weeks of therapy with nelfinavir plus indinavir with acceptable tolerability, Stage B begins. In the 2-week, randomized, double-blind phase of Stage B, patients receive either indinavir plus nelfinavir (Group B1: 9 patients) or indinavir placebo plus nelfinavir placebo (Group B2, 3 patients). After 2 weeks, all patients in Stage B (including those originally assigned to receive placebo) receive open-label indinavir plus nelfinavir for the remainder of the 24 weeks.