Update for Windows Mail Junk E-mail Filter [April 2011] (KB905866) will not install on my PC {vista OS}

Update for Windows Mail Junk E-mail Filter [April 2011] (KB905866) will not install on my PC {vista OS}

Update for Windows Mail Junk E-mail Filter [April 2011] (KB905866) will not install on my PC {vista OS}
 
Fixes?