Since you say that the start menu disappears after you move the mouse, I assume that you don't have Circle Dock set to disappear after you click on an icon/centre. The problem is that the icons in Circle Dock will grab focus when you mouse over them, which causes the start menu to disappear. I don't have a workaround for this other than to set Circle Dock to hide after you click an icon.
For the start menu not showing up after shadows are disabled, try opening the start menu from the Windows taskbar and see if it still works there. Then try opening it from Circle Dock.