Is your computer infected with a virus that is preventing you from downloading security updates from the Internet or from running any antivirus program on that machine? Or are your looking for an antivirus software that can be carried on a USB drive to quickly scan any disconnected computer(s) for viruses or malware?

You should check out Microsoft Safety Scanner. This is a free antivirus software, always updated with the latest definitions, and requires no installation - all you need to do is copy the program executable msert.exe to an infected computer and double-click that file. If it detects a problem, the infected files will be quarantined.

You may either do a thorough scan - check every file and folder - or a quick scan that checks a limited number of folders that are most likely to contain viruses, malware or spyware.

Microsoft Safety Scanner is available as a free download for both 32-bit and 64-bit version of Windows. You may use on Windows XP, Vista or Windows 7 machines and, unlike Microsoft’s other antivirus software, Safety Scanner doesn’t perform a check for genuine Windows.

The program expires after 10 days but you can always re-download it with the updated virus definitions. It won’t however scan your Outlook emails or your network drives for any possible infections.