support.microsoft.com/en-us/kb/2519899

If you right-click a red flag in a “Windows Security Alerts" icon on the right side of the task bar, and then click Open Security Center, a message that reads "The Security Center service is turned off" is displayed in the Windows Security Center ...

www.vistax64.com/system-security/197568-security-center-serv...

I am using Windows Vista on my laptop and noticed my windows security alerts were a red shield. When I clicked on it to see what the problem was I see the Security Center is turned off. When I click on "Turn on now" I get the error message THE SECURITY ...

answers.microsoft.com/en-us/windows/forum/windows_vista-secu...

A couple of weeks ago I updated this computer with SP 2 and then after restarting I updated to IE 8 from Windows Update. Ever since updating I have had the security center alert balloon pop up at start up on the task bar saying I have a security a ...

answers.microsoft.com/en-us/windows/forum/windows_7-security...

I have a Windows 7 x64 machine.

I had a virus, and just after removing it I discovered that both Windows Update Service and Windows Security Center Service have been removed.

I reinstalled Windows Update Service, but couldn't find where ...