To all who helped with suggestions a big thank you. The problem turned out to be cuased by Microsoft Wireless Keyboard and mouse sets. Two users had requested these and they were issued by the IT department. The users had then returned the keyboards but kept the mouse and receiver. It turns out that if the receiver loses touch with the keyboard it causes strange things to happen on the laptop keyboard. Ctrl sticks arrow keys stop working etc. Return the wireless keyboard and the problem dissappears. Hope the solutions help someone one day. Frustrated Admin