Mouse Right Click Menu

When Right Click the mouse in blocks screen an Menu appears, any one of the option from the menu is selected automatically.

What do you mean?

when right click of mouse, from this list near mouse cursor is automatically selected

see this picture, am not selected, just i done right click of mouse button

This looks like a sticky right mouse button.
I had this effect when my keyboard slid over and pressed against the right side of my trackball.

Do you have a spare mouse you can try?