Right click doesn't work

When I try to right click and drag a file or a folder to copy it or make a shortcut in Windows (Windows 7), it doesn't work. I only get a purple line following the mouse-arrow "drawn" on the screen(!) , which disappears when I let go of the button. Right clicking on a file or a folder to get options works fine. It's only right clicking and dragging that doesn't work. Not with the touchpad or with a mouse. I have tried adjusting the options for the mouse in control panel, but nothing seems to help.

Does anybody know how I can fix this?

Thanks