|If this is a fault then I'm a bit short on ideas about it. |
However, if you left click the mouse and then move the mouse just a bit, an outline of a rectangle will start to appear until you release the left button. This is normal and allows you put a box around a group of icons to highlight them and then use a further click to drag them into a new desktop position. Maybe you just hadn't noticed this feature before.
If it's something other than this let us know - maybe someone will have some ideas.
We all live on the same ball.