To determine the maximum tolerated dose (MTD) of WR 6026 in HIV-infected patients. To determine whether any unexpected toxicities are caused by WR 6026 in HIV-infected patients. To determine whether there is additional toxicity when WR 6026 is given for 21 days rather than 14 days. To further investigate the pharmacokinetics and pharmacodynamics of WR 6026, and in particular to examine potential correlations between the area under the concentration-time curve and methemoglobinemia or other toxicities.