File "corrupt"
If a file is not saved properly, can sometimes open a dialog box that says "file ...... corrupt." To click on the details button, you'll see that you can still open the file, you jsut have some weird things going on in the music that the program doesn't like (ex. too many beats in a measure). Perhaps better terminology to avoid confusion?
Comments
That means your score must be repaired. See how: https://musescore.org/en/node/54721
If you encounter difficulties, attach your score, someone from us will probably help you. And, of course, any clue you can provide on the origin of this problem will be welcome.