This problem can have multiple causes. Due to the fact that you saved your data to C:\ drive, it's advised to always run the program using Administrator rights. To do this, right click on its icon and select Run as administrator. Also, make sure that your files are saved with a proper file extension. While you have the "select controller" window open, make sure that you have selected all files on file format section.
It is also a good idea to uninstall the product and install it again. This is advised because the program, on the installation process, will automatically search your computer for compatible files. This way, the program might recognize the other files from your computer.