DXF/DWG Fix From Adobe (CS3)

You can find more details about the replacement plugin to fix this issue here.

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As about this plugin, you must meet the installation requirements:

To use the DWF/DWG plug-in, you must meet these requirements:

• Illustrator CS3 13.0 or greater installed
• Mac OS 1.4.8, Mac OS 10.5, Windows XP with Service Pack 2, or Windows Vista

Full list of intructions and download available here.