If you think your computer has a virus that your current antivirus software missed or is unable to remove, the Security Scanner helps remove viruses, spyware, and other malicious software. The Microsoft Security Scanner will work with your existing antivirus software but it is not a replacement for a resident antivirus software program. There is no charge to use the Microsoft Safety Scanner.
The Microsoft Safety Scanner expires ten (10) days after being downloaded. In order to scan after that time, download the Microsoft Safety Scanner again in order to get the latest anti-malware definitions.
As illustrated by the following images, the scanner is easy to use. You can download the Microsoft Safety Scanner for running on your own computer or to removable media (i.e., a thumb drive) and transport it to another computer that is infected.
Clicking the "Download" button, provides a prompt to select the 32-bit or 64-bit version.
If you are downloading the scanner for use on a different computer, be sure you know the correct operating system (32- or 64-bit)
Save the file to a convenient location. When launching, Windows 7 and Windows Vista users will be asked to approve a UAC prompt.
After launching, you are presented with an end user license agreement. The terms must be accepted in order to run the scan.
ScanningOne more Next click to get to the point of selecting the type of scan you want the scanner run.
Knowing my computer is not infected, I selected a Quick scan.
To provide "breathing space" on an infected computer, run a Quick Scan first and then follow with a Full scan. If you have a lot of files, the scan may take up to several hours to complete. Allow plenty of time for the scan to run to completion.
The Quick Scan was indeed fast and only took a few minutes to complete.
After the scan has completed click Finish to close the program.
Remember, the Microsoft Safety Scanner is not a substitute for a resident antivirus software program. It expires ten (10) days after being downloaded. In order to scan after that time, download the Microsoft Safety Scanner again in order to get the latest anti-malware definitions.
Should you need to re-examine the log, it is located at C:\Windows\Debug\msert.log. If errors were found during the scan see Microsoft Safety Scanner Troubleshooting.
Download: Microsoft Safety Scanner
If you are confused about the difference between the Microsoft Security Scanner and the other anti-malware tools provided by Microsoft, my follow-up article, Understanding Microsoft Anti-Malware Software, should help clear up the confusion.
Updated Information at Understanding Microsoft Anti-Malware Software 2012.