First of all, thank you very much for your fast answer! But I don't understand exactly what you say, could you explain a little more please? (a1) Do you mean that the TrustedInstaller still has rights now, even now it's not the owner anymore? (a2) That would mean that future updates and service pack installs would still run fine? (b1) Do you mean that, even now the TrustedInstaller has rights, I still have to add him to the Administrators group? (b2) Is that just to be sure? (c1) And what do you mean by 'this may not be enough no'? That sounds alarming to me! (c2) Would you advise a reinstall? (c3) In case of a reinstall, I would have to activate Vista again, I don't think Microsoft would let me? Thank you very much for your answer in advance, Kind greetings, Jeroen >> the trusted installer would still to have rights to read and write those files still, either add it to the admin group, or make sure any files you change that you still give it rights to be able to read and write. this may not be enough no