HiI had the same problem. It is because if you have a "no CD patch" on FS9, it is most likely the version 9.0 patch. If you replace it with the 9.1 version patch it then the MD11 should install fine (It did on mine). The version 9.1 "no CD patch" can be found here: http://www.simugold.fsnet.co.uk/files/nocd2k4patched.zip Hope that helps.