Information
Uncontrolled installation of applications can introduce various issues, including system instability, and allow access to sensitive information. Installation of applications must be controlled by the enterprise. This setting prevents unsigned gadgets from being installed.
Solution
Configure the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Windows Sidebar -> 'Disable unpacking and installation of gadgets that are not digitally signed' to 'Enabled'.
To turn off Windows Sidebar completely, configure the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Windows Sidebar -> 'Turn off Windows Sidebar' to 'Enabled'.