Make sure you are downloading the Mac version and follow the installation instructions:
"Once you have downloaded the Firefox 1.5.dmg file, double click the Firefox Disk Image to open it in Finder, and then drag the Firefox application onto your hard disk. Drag the icon to your Dock if you want it to appear there."
This seems ( I am no Mac expert) to say hat you must save the file. then use a Mac utility to install it.
Edited by jgweed, 27 December 2005 - 07:17 PM.