Maybe you are running out memory:
- reboot
- start shotcut and nothing else
- open the project but do not play it
- export and wait for it to finish before starting anything else
Also, I see you are using the 32-bit version. It is less stable, can only use up to 3GB RAM, and has been discontinued. So, limited memory is the most likely problem. Use 64-bit if you can. Otherwise, reduce tracks if you can. 4 tracks of 1920x1080 is a lot for this 32-bit program.