"Invalid Project File" - What exactly does this mean?


I was working on a project yesterday, everything was fine, but when I went to load it today, I got the error message “Invalid Project File”. What exactly makes the project invalid? What can I do to attempt to fix this?

However, I have a feeling that it may be my USB stick which is broken. I have just plain audio files on it which I used in my project, but now when I try to open them, nothing happens. I don’t even get an error message saying that the file is corrupted or anything…

Is my project corrupt, or is my memory stick broken? I really don’t want to have to start from scratch, but that’s they way it’s starting to look… :frowning:

(Would the project open if I downloaded the audio files again? I used loops I downloaded from online, so if I re-download them so I know they work, would that fix this?)