Windows Forums member Uvais, who is always on the lookout for other users’ safety on their PCs shares a tool recently released by Microsoft: Microsoft Safety Scanner, which is designed to work with your current anti-virus software to detect threats and infections on your PC. From the download page:
The Microsoft Safety Scanner is a free downloadable security tool that provides on-demand scanning and helps remove viruses, spyware, and other malicious software. It works with your existing antivirus software.
The software is designed to be downloaded for one-time use and expires after 10 days–requiring you to go back to the site and download the latest version with current virus-checking definitions.