Standalone client in some situations cannot be minimized.
Even if you ALT+TAB elsewhere, then you click in bottom-right corner of taskbar to show desktop, so all apps should be minimized now, then you call some app from your taskbar.
The app will open, but so do the CF Client in background, so it completely overlays the system taskbar.
so … result:
So if you minimize the client, it should stay minimized until called, not like whenever it wants.