I have a few DivX movies, and I downloaded the 3ivx D4 PR1 Decoder for OS X, and 3ivx Doctor II. I read the instructions for installation in OS X for the 3ivx D4 PR1 Decoder, in which it says for OS X, you must put the decoder in the QuickTime folder, which is in the Library folder, at the root of your system. So, I tried to do so, but I get an error telling me that the QuickTime folder cannot be modified. Now, I am the first and only user on this computer, so what is the problem? Has anyone encountered this before?