The purpose of this study is to study the safety and efficacy of Amprenavir/ritonavir or saquinavir/ritonavir in HIV infected patients that have failed Kaletra as their second protease inhibitor based HAART.

Inclusion:

• Subject must remain on current antiretroviral therapy during screening until a new regimen is initiated.
• Subject demonstrates reduced susceptibility to lopinavir.
• Subject's two most recent viral loads obtained after at least 16 weeks of lopinavir/ritonavir therapy, and while still on Kaletra therapy must be at least 1,000 copies/mL.
• The Kaletra regimen must be the subject's second PI containing regimen and must not contain any other PIs.
• Subject is at least 18 years of age.
• Subject has not been treated for an active opportunistic infection within 30 days of screening.

Exclusion:

• Subject has a history of active substance abuse or psychiatric illness that could preclude compliance to the protocol.
• Female subject pregnant or lactating.
• Use of an Investigational drug within 30 days prior to the initiation of drug dosing.
• Subject is receiving systemic chemotherapy.
• Subject has a history of acute or chronic pancreatitis.