I have a project that has several reports in it. I have built the project into an app. Sometimes I run the app and I get the message 'file does not exist'. I go back to my project, and the report is in the project. Why does it do this?

I recently found an instance where this happens every time. I have an executable that calls different apps. When I go to the first app, it runs all my reports fine. When I exit the app (which takes me back to the executable) and go to another app, I consistantly get the message 'file does not exist' when I run 'report form xxx preview'. It doesn't matter which app I run first or second, the results are the same.