Unmarked time signature changes?

I changed the page format before noticing that some measures had extra rests in them. I tried just deleting the rest, but it seemed as if they were meant to be there. I don't know if the format had anything to do with it. The song is in cut time, but certain measures have five or five and a half quarters instead of four. Selecting the whole measure and clearing it with delete cures the problem. I've never noticed this happening before. Also, it keeps saying the file is corrupted even after I copy and paste the notes into a new score. Not sure if this is related.