Inclusion Criteria:

1. Signed informed consent prior to trial participation.
2. HIV-1 infected males or females >=18 years of age.

3. Screening genotypic resistance report indicating both of the following:

   • at least one primary PI mutation at the following sites 30N, 46I/L, 48V, 50V, 82A/F/L/T, 84V or 90M , and
   • no more than two protease mutations on codons 33, 82, 84, or 90 .

4. At least 3 consecutive months experience taking ARVs from each of the classes of NRTI(s), NNRTI(s) , and PIs at some point in treatment history,

   • with at least 2 PI-based regimens (minimum 3 months of exposure of each), one of which must be part of the current regimen, and
   • current PI-based ARV medication regimen for at least 3 months prior to randomisation.
5. HIV-1 viral load >=1000 copies/mL at screening .

6. Acceptable screening laboratory values that indicate adequate baseline organ function. Laboratory values are considered to be acceptable if the following apply:

   • Total Cholesterol <=400 mg/dl or 10,36 mm/L (<=CTC Grade 2).
   • Total Triglycerides <=750 mg/dl or 8,5 mm/L (<=DAIDS Grade 2).
   • ALT <=3x ULN and AST<=2.5x ULN (<=DAIDS Grade 1) .
   • Any Grade GGT is acceptable.
   • Any Grade creatinine kinase is acceptable as long as there is no concurrent myopathy.
   • All other laboratory test values <=DAIDS Grade 1.
7. Acceptable medical history, as assessed by the investigator, with chest X-ray and ECG within 1 year of study participation.
8. Willingness to abstain from ingesting substances during the study which may alter plasma study drug levels by interaction with the cytochrome P450 system (listed in Section 4.2.2 and Appendix 11.7 of protocol).
9. A prior AIDS defining event (as listed in Appendix 11.1) is acceptable as long as it has resolved or the patient has been on stable treatment for at least 2 months. (AIDS related complex is acceptable.)

Exclusion Criteria:

1. ARV medication naïve.
2. Patients on recent drug holiday, defined as off ARV medications for at least 7 consecutive days within the last 3 months.
3. ALT >3x ULN and AST >2.5x ULN (>DAIDS Grade 1, refer Appendix 11.3) at either screening visit.

4. Female patients of child-bearing potential who:

   • have a positive serum pregnancy test at screening or during the study,
   • are breast feeding
   • are planning to become pregnant, or
   • are not willing to use a barrier method of contraception, or
   • require ethinyl estradiol administration
5. Prior tipranavir use.
6. Use of investigational medications within 30 days before study entry or during the trial. (T-20 [enfuvirtide] and Tenofovir (Viread), investigational at the time of writing of this protocol, will be allowed.)
7. Use of immunomodulatory drugs within 30 days before study entry or during the trial (e.g. interferon, cyclosporin, hydroxyurea, interleukin 2).
8. Inability to adhere to the requirements of the protocol, including active substance abuse as assessed by the investigator.
9. In the opinion of the investigator, likely survival of less than 12 months because of underlying disease.