Thank you for responding to my question. I checked that the file is a DSS file. Also, I am using the Pro version of Express Scribe. I put in my registration code again and it accepted it (again). I restarted my computer, opened up Express Scribe, and I still get the same message.
As I said previously, I have had this product a long time and have used it to open the same type of files, even .wav files, and never had this issue. I even went back and opened up voice files that previously I wasn't getting this message on, and I am getting the message. How do I get rid of this message?