and not recommended as a 'cure for all'. Try disabling AVG for this one download and install. It may be preventing the tool from installing and running properly.
Mark
Hi Hi! I keep being prompted by Windows Update to download the Windows Malicious Software Removal Tool - December 2009 (KB890830). To date I have given the PC access to download this software 7 times over the last few days and all 7 instances show up under the update history as being successful downloads yet if the pc is restarted or even within a few minutes of one instance being downloaded, the windows update icon will return prompting to download the SAME tool. I am currently using Windows Vista Ultimate, service pack 2. This is a HP Pavilion A1007w desktop PC. I have ran malwarebytes and SUPERAntispyware on this PC and no infections were found. I also have AVG Internet Security 9.0 running as my anti-virus/firewall software.

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