Red X markings appear

I'm posting on behalf of my mother, a Ventura 10 user. She asks:

Sometimes when I draw frames inside each other, or overlapping, a red X appears over the entire page, and all text on following pages disappears.
Usually if I delete the offending frames all is well again.
This time I have page 7 in a file showing an irremovable red X. I did move frames around in a foolish way, one complete with pic & caption coming right down over the footer. I have managed to delete that pic and caption frame, but the big red X rermains immovable, and I have lost all text on the following several pages.

Can anyone please offer any thoughts or suggestions?

Many thanks

Aidan