This little fault puzzled me today. I found that I was unable to click and drag any icons within the Windows Explorer windows. It was very frustrating to say the least. But you will never guess what solved it for me.
Solution: Hit the ‘ESC’ key.
That’s right. Simply hitting the escape key on my keyboard return the click’n’drag function.
Reading around some forums from people experiencing the same thing, speculation is some utilities may expectantly lock this function and hitting the escape button releases the lock.