Sticky autoshape

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I put an autoshape round some text, then tried to copy/drag it to produce another of the same .I've now ended up with two autoshapes but the 'copy' will not allow itself to be selected. This means I can't move it or re-size it in the normal way. The only way to remove it is to delete a chunk of text near it and then paste that text back. But all sorts of other actions can bring back this damned autoshape! Why is it so resistant to attack?