Observational Study Of A Protease Inhibitor (PI) Containing Regimen In Subjects With PI Mutations Selected During Prior Treatment With GW433908 (Fosamprenavir)

Inclusion criteria: * Prior participation in study APV30005 AND one of the following studies: APV30001, APV30002, AZL30006, APV30003. * Must be failing virologically (\>1000 copies at two consecutive time-points) and have a screening genotype with evidence of at least one new APV-associated protease mutation: V32I (+/- I47V), I50V, I54L/M, I84V acquired since commencing treatment with GW433908. Exclusion criteria: * Have 2 or more of the primary resistance mutations D30N, G48V, V82A/F/T/S and L90M. * Have a medical need for use of an non-nucleoside reductase transferase inhibitor (NNRTI). * Have an acute CDC Class C event requiring therapeutic intervention. * Are pregnant or lactating. * Have any other condition which in the opinion of the investigator would preclude their participation.