Are you able to fix the filenames of the tutorial PDFs on the obinary website? the UserGuide and Tutorials seem to be .gz files with a .pdf filename, so the links don't work directly in IE or Mozilla, at least not for me .. I had to manually download them. If you just unzip the files that would probably be best, since unzipped they are more or less the same size.. The files are stored uncompressed on the server - magnolia will compress them on the fly if your client accepts compressed content. So it seems there is some other problem, maybe wrong headers or such.