Thank you for your post.
Are you able to manually enter a value into the field without the use of the script? If you created a new script (do not duplicate), do you still crash? If you create a new layout with a new instance of the field and execute the script, do you still crash?
I have now been able to resolve this, the offending script was a Go To Field command set on the field exit action.
I don't understand why this would cause it to crash. Would it be because of a tab order that already existed on that field and when a script was set on the same field to move to the next field, it caused a crash?
So the situation was field 1 had a script on object exit that used a Go To Field command to go to the next field 2, and at the same time there was a tab order from field 1 to field 2.