Patients not previously enrolled in clinical trials of Preveon are randomized to 1 of 2 doses of Preveon orally once daily and L-carnitine orally once daily. [AS PER AMENDMENT 7/8/98: Patients must receive other antiretroviral agents concomitantly with Preveon; at least 1 other antiretroviral agent must be added with Preveon that was not previously administered to the patient.Patients previously enrolled in Preveon clinical trials who "roll in" to expanded access and who have received at least 16 weeks of Preveon receive open-label Preveon orally once daily and L-carnitine orally once daily, taken with or without food at the same time each day.] All patients enrolled in expanded access are randomized in a 1:1 fashion to 1 of 2 doses taken orally once daily. Patients initially assigned to the higher dose will have their Preveon dose reduced to the lower dose at Week 16 of treatment. Patients initially assigned to the lower dose continue this dose unless dose modification to an even lower dose for toxicity is required. [AS PER AMENDMENT 7/8/98: Additional informed consent is needed for this reduction due to limited efficacy of the lower dosage in treating HIV infection.]