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FF 4.0 "Cannot open...Not supported by this architecture."

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I downloaded FF 4.0 to my iMac G5, running OS X , 10.5.8, put it in my application folder, and then dragged it to the dock.

The logo had a "forbidden" sign superimposed, and when I tried to open FF, received the message: "Cannot be opened...not supported by this architecture."

I downloaded FF 4.0 to my iMac G5, running OS X , 10.5.8, put it in my application folder, and then dragged it to the dock. The logo had a "forbidden" sign superimposed, and when I tried to open FF, received the message: "Cannot be opened...not supported by this architecture."

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Firefox 4.0 doesn't work with PPC Mac's.

For older Macs that aren't supported in Firefox 4.0, try TenFourFox for PowerPC's running Mac 10.4.11 & 10.5.8 .
http://www.floodgap.com/software/tenfourfox/