Notes about the ICNS file extension:
Incorrect file associations could be the result of underlying issues within your PC system. As such it is highly recommended to scan your PC for invalid registry entries
, unused processes and other unfavourable system settings to identify slowdown issues.
The ICNS file type is primarily associated with 'Macintosh OS X' by Apple Inc.. ICNS files are icon files for the Macintosh operating systems. They are different from Windows .ICO files in that they act like a container with individual icon resources enclosed within it. ICNS file images are not displayed outside the icon, but are enclosed inside the files as data.