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When I download Firefox, the icon has a circle/cross bar through it and will not upload to my Mac 10.4.11 hardrive.

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After moving the icon to my application folder, when I try to open it, the message is:

You cannot open the application "Firefox" because it is not supported on this system.

After moving the icon to my application folder, when I try to open it, the message is: You cannot open the application "Firefox" because it is not supported on this system.

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Firefox 4 requires at least OS X 10.5 and an Intel Mac. There is a third party version of Firefox 4 that runs on OS X 10.4/10.5 and PPC Macs, for details see http://www.floodgap.com/software/tenfourfox

If you prefer, you can get the latest version of Firefox 3.6 from http://www.mozilla.com/en-US/firefox/all-older.html

Mozilla are working to prevent Mac users with non-compatible systems from getting the notification about Firefox 4, and also not displaying the "Download Firefox 4" button on http://www.mozilla.com

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Thanks. That was very helpful.

Is sthe 3rd party Firefox 4 trustworthy and represent a significant improvement over Firefox 3.6?

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Very helpful. Solved my problem. Turns out I can't use FF 4 because I don't have Mac OS 10.5. I have Mac OS 10.4.11. The link provided in the answer allowed me to reinstall FF 3.6.16 on my iMac. QUESTION: Am I better off sticking with FF 3.6.16 (which FF will support for only a short time) or should I go to the third party version of FF 4? Does anyone know or have a guess?