Don't know why, but i noticed that it happens to me.
I use to put the icons on the desktop here and there not in an arranged manner but in free style as i like.
But whenever i refresh the desktop by pressing the F5 button for a long time it arrange the icons one by one which i hate the most.
At first i thought that its just a mistake or by chance but i noticed it repeatedly.
As a result now i have to turn my habit of long refreshing and must have to use the F5 button for smaller times which is not likable.
Microsoft must fix it.