What is "stamp copy"? Is it stamping, i.e. what happens when you press S? How do you know you can't copy anything? Is the selection rectangle not shown? Is the "one time" counted from when you launch TPT, or is there something you can do to reset it? E.g. does opening a save fix it such that you can stamp something one more time and then it breaks again? Do you have scripts loaded? Is "latest build" the version that is available here? Does "PC" mean windows in your case?