Unable to install from downloaded disk image file My Mac G4 (running OS X 10.3.9) won't install from any .dmg file I download. It keeps popping up a message: "name of setup &amp; no mountable file system" or "application file cannot be found". Is there some setting I need to change to get around this problem as I need to install some extra programs urgently.
It is likely the disk images do not support Mac OS X 10.3.9.

The command line tool used to create disk images is called hdiutil. This hdiutil manual page documents the DMG format's history and compatibility with older editions of Mac OS X.

hdiutil manual page