postmessge for mouse click problem

[fjlj]

i am currently using PostMessage to send some WM_MOUSEMOVE messages to a window and then i am sending WM_LBUTTONDOWN followed by WM_LBUTTONUP witch works just fine..... BUT when the click happens my mouse cursor will jump to the far left of the window i am sending messages to. this happens on clicks only not on movements.. anyone know why this is happening and what i can do to fix it?

thanks