I still can drag and drop it onto my pcb and use it but I never have faced this 'forbidden' sign phenomenon before. When working on a pcb and adding a component to it by selecting the one I want and drag and drop it onto the pcb, selecting and clicking on it in the 'core parts' with the mouse, a 'forbidden' sign (red circle with diagonal line) pops-up.
Working with the latest version 0.9.3 (thanks again MBantz ), I am suddenly facing a strange problem with the Fritzing program.