Participant's Zoom Crashes When I share my screen

Hello, Twice now, one of my participants has had the zoom call from my personal meeting room crash right when I go to share my screen (to show a video). She has the Zoom program installed on her PC laptop but I use Mac and NEVER have this problem with anyone else (she can't remember which OS it has but said it is an "old" laptop). We tried repeatedly and each time I shared my screen, the program just closed. When she used the hyperlink to join my private meeting room, it worked (although she was warned she would be joining a different meeting so she said "cancel") and brought her back to me. Then as soon as I shared the screen to show the video, she saw it for a split second and then she lost me completely. She was able to hear me but the program disappeared from her computer.
What should we do? I use the free version of Zoom.