[Vadikan]

нужно запретить пользователю любые манипуляции с языковой панелью

Так и надо писать в заголовке.

USER Administrative Templates\Control Panel\Regional and Language Options Restrict selection of Windows menus and dialogs language At least Microsoft Windows 2000 This setting restricts users to the specified language by disabling the menus and dialog box controls in the Regional and Language Options Control Panel. If the specified language is not installed on the target computer, the language selection defaults to English. Код: HKCU\Software\Policies\Microsoft\Control Panel\Desktop!MultiUILanguageID

USER Administrative Templates\Start Menu and Taskbar Do not display any custom toolbars in the taskbar At least Microsoft Windows XP Professional or Windows Server 2003 family This setting affects the taskbar. The taskbar includes the Start button, buttons for currently running tasks, custom toolbars, the notification area, and the system clock. Toolbars include Quick Launch, Address, Links, Desktop, and other custom toolbars created by the user or by an application. If this setting is enabled, the taskbar does not display any custom toolbars, and the user cannot add any custom toolbars to the taskbar. Moreover, the Toolbars menu command and submenu are removed from the context menu. The taskbar displays only the Start button, taskbar buttons, the notification area, and the system clock. If this setting is disabled or is not configured, the taskbar displays all toolbars. Users can add or remove custom toolbars, and the Toolbars command appears in the context menu. Код: HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer!NoToolbarsOnTaskbar

Источник: Group Policy Reference