The study will consist of 2 stages. In the 1st stage we aim to find the right dose of nelfinavir to combine with CRT, and this will require around 27 participants of whom up to 18 will receive nelfinavir together with CRT. In the 2nd stage, we want to find out the benefits of this approach over and above standard treatments and therefore we will recruit the order of 262 participants and allocate 170 to 1 of the 5 following treatment arms: