The sidebar is enabled by default in most new installations of MS Windows Vista and MS Windows 7. Microsoft has confirmed potential security issues with this and has issued a fix that disables the Sidebar and Gadgets to mitigate the vulnerability.
From the article:
“Revision Note: V1.0 (July 10, 2012): Advisory published.
Summary: Microsoft is announcing the availability of an automated Microsoft Fix it solution that disables the Windows Sidebar and Gadgets on supported editions of Windows Vista and Windows 7. Disabling the Windows Sidebar and Gadgets can help protect customers from vulnerabilities that involve the execution of arbitrary code by the Windows Sidebar when running insecure Gadgets. In addition, Gadgets installed from untrusted sources can harm your computer and can access your computer’s files, show you objectionable content, or change their behavior at any time.”
http://technet.microsoft.com/en-gb/security/advisory/2719662