The file extension CMX marks files containing image data in Corel Metafile Exchange format. This proprietary format is used by several programs from Corel, especially Presentations. The files can include raster images as well as 2D vector graphics as well as metadata. Corel Mega Gallery Clip Art data is also saved in this format.
Unlike current, earlier versions (before CS) of Adobe Illustrator supported this format.
Most often resolving problems with opening CMX files is very simple. Just install an appropriate program that supports such files. All of the listed programs support CMX files, but may vary in offered function and purpose. Some programs may be capable only of viewing contents of CMX files or offer file conversion options, but may not be capable of editing such files.
It is possible that although a compatible program has been installed on user’s system, it is not used by the system to open it. This may happen because no default application was associated with this type of files. To associate CMX files with given application, select "Open with" from drop-down menu (accessed by right-clicking on the file). Then select from the list the program or application you want to be used to open this type of file. If the Inkscape applications is not on the list, select "Browse" option in order to manually locate the directory where Inkscape has been installed.
Sometimes problems with opening CMX files may not lie with the application itself, but can arise due to other causes, such as: