If you using Windows Vista,You already have windows defender. Ensure the version of the defender because if Windows Defender informed you that an update is available, you are running an older version.
Below are Windows Vista Supported Antispyware Product as of the latest release of the Cisco Clean Access software.
Product version - 1.x
AS Checks Supported
(Minimum Agent Version Needed) are:
Installation - (4.0.5.0)
Spyware Definition - (4.0.5.0)