You may have experienced the little message that says “Explorer has performed an illegal operation and will now close” and a few other words to that effect.
While working on a faulty PC our most senior workshop engineer once found that he could not get this message to close despite utilizing his vast array of diagnostic skills. After half an hour of frantic fault finding he smelt a rat when the message remained even with the screen switched off.
James is now renowned for his ability to “Cut and Paste”