Error in spacing between staves

Hi all,
I already tried to post this but can´t see the post anywhere. If moderators have to approve a post before publishing, then this is just a duplicate.
The thing is the following: I use Musescore to notate my piano pieces. I just opened a piece to work on it and found that at a couple of spots, there is an abnormal (and unacceptable) spacing between the two staves. In the first place the separation is just absurd. In the second place, the separation is not as exaggerated but still quite a bit wider than in the rest of the score. It is like the formatting of the page is behaving randomly. I´m just checking my other pieces and this is something that comes up every now and then. I enclose a screen shot and would be grateful for any information about how to solve this.