Users of Windows Vista and Windows 7 have been advised to completely disable their Windows Sidebar and Gadgets, in response to what appears to be a serious security risk.
Read about it here :- http://nakedsecurity.sophos.com/2012/07/12/disable-windows-sidebar-gadgets/?utm_source=Naked+Security+-+Sophos+List&utm_medium=email&utm_campaign=fb4d853f07-naked%252Bsecurity
Microsoft Fix it :- http://support.microsoft.com/kb/2719662