Microsoft Windows Malicious Software Removal Tool is basically a free tool which helps to remove specific malicious software from computers which run Windows operating systems, including all versions of Windows Vista. This tool is updated on the second Tuesday of every month and it is distributed via Windows Update. After it is installed, it silently runs in the background and removes the malicious software that it finds. When the detection and removal process is complete, the tool generates a report describing the outcome of the scan. The report can be found in a log file named 'mrt.log' placed in the 'C:\Windows\Debug' folder.
Even though this tool helps you remove malicious software, it should never be used as a replacement for an antivirus program. That's because this tool has a very limited database of malicious software and searches only for specific threats. Also, it is updated on a monthly basis unlike antivirus solutions which are updated daily.
Where to find it?
By default, the tool can be found in the 'C:\Windows\System32' folder. Once you open this location, search for a file called mrt.exe.
If you don't find this file, it means that this tool is not installed on your PC. In this case you can download it directly from the Microsoft Download Center.Download at this link:
http://www.microsoft.com/downloads/details.aspx?familyid=ad724ae0-e72d-4f54-9ab3-75b8eb148356&displaylang=en
If you want to run this tool manually, go to the location mentioned above and double click the mrt.exe file. An easier way is to type mrt.exe in the Start Menu Search Box or in the Run window.