To study the anti-HIV activity of the various doses of Ro 24-7429 monotherapy based on virologic and immunologic endpoints. To study the safety and tolerance of Ro 24-7429. To explore relationships between exposure to Ro 24-7429 and its metabolites and antiviral activity and drug toxicity. To determine a safe, tolerable, and active dose regimen of Ro 24-7429, and to make preliminary observations of Ro 24-7429 in combination with another antiretroviral nucleoside.