I am trying to add some of my AVI files for conversion in Digital Media Converter, which keeps giving me the message "Unable to render" and doesn't add the files.

In order to convert an AVI file, you must have the video and audio compressor in use by that file installed on your computer. Try opening your video file in Windows Media Player. It may be able to determine, download and install the appropriate compressors. You will also find our article on Understanding Compression in AVI useful: https://www.deskshare.com/Resources/articles/Compression_AVI.aspx