I have IFXv4.5, but I think I've only got installed IFXv4.0 currently, as I never really gained much from v4.5 personally. I know there are PPC plugins/addons with v4.5, and they never were really useful for me in the past. I have v4.5 tucked away somewhere, so I cannot lay my hands on it at the moment to offer you some support on the subject, which I would if I could, but I hope someone is able to explain to you why the error message(s) pop-up, and offer a solution/fix.