I am sorry to hear you are having problems.
Try using the "Insert dismounts" mission. It will do exactly what you are trying to do automatically. I would really need a little more info on the exact sequence of orders you are giving in order to understand why the dismounts are doing what you describe. But the Insert dismount order will cure the problem anyway.
Check the function reference section of the manual for keyboard shortcuts. They will dramatically reduce the ammount of clicking you have to do.
To answer the crashing issue, I will need more info about your system (OS, memory, video card, video memory, etc.). If you would prefer not to post it here, you can send it to
techsupport@prosimco.com