Repeating Windows Update\ Windows Malicious Software Removal

Hi Hi! I have noticed over the last week that the Windows Update icon continues to show I have a new critical update to be installed. I will go ahead and do this installation, it makes its registry backup, and it will say it is successful and if you look in the history of successful downloads it will show there as well for all the times I have downloaded it YET when the PC is restarted, the icon will be back again or sometimes in just a few minutes after the first instance was allegedly downloaded. The update is Windows Malicious Software Removal Tool - December 2009 (KB890830. To date I have 7 different instances of the same download showing the update history. I am using Windows Vista Ultimate, Service Pack 2. I have used malwarebytes and SUPERAntispyware to scan the PC and it has found no infections. I have AVG Internet Security 9.0 as my anti-virus and firewall. ***BTW***I have noticed my PC is being a lot slower and does windows explorer does freeze which prompted me to think infection, yet nothing is being found***