If the Isoview software doesn't open the illustration, I recommend removing it from your PC (Control Panel > Uninstall a program) and then install it again. The problem can occur either because the software is not installed properly or the illustration file is corrupted. After the installation process is complete, try opening the illustration. If you receive the same error, try opening another illustration. If you still can't open them, I suggest you contact the developers of the application.