Error saving project

I have Audacity version 2.1.0, and I have recently been having the problem where it will not let me save my file, and will come up with an error screen. Occasionally the error alert reads differently, but I have attached a picture of the most recent problem. This understandably, is causing some difficulties, as I have been losing a lot of progress on my work. Most recently, I had just finished converting a stereo track to mono, and when I attempted to save my work, I was not allowed to do so. Any thoughts on why this is happening and how I can prevent it?
Screen Shot 2015-07-01 at 3.35.25 PM.png

Please install Audacity properly rather than run it from the DMG, then you won’t have the problem: