I can't save a project

I am using windows 10 pro and I recorded an album side so that I can break it up into the tracks to add to my mp3 player, however when I attempt to do so, the program will not let me save the project. I tried to save the project, but it keeps giving me an error message: “file not found, check the name and try again.” I have tried various ways of doing it, but I can NOT get this file to save. Any ideas???

Which version of Audacity? (Look in “Help menu > About Audacity”.)