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Fix Microsoft Safety Scanner Reporting Infections But Finding No Malware

Khadija Khan Oct 9, 2026 868 views

Question details

The user is confused because Microsoft Safety Scanner flags multiple files as infected during the scanning process but concludes the scan by stating no malware was detected, while the computer continues to freeze on web pages.

Fix Microsoft Safety Scanner Reporting Infections But Finding No Malware

Product: Microsoft Safety Scanner
Device & OS: Windows
Scenario: Running a system scan to resolve web page freezing and performance issues.
Observed behavior: The scanner's active counter indicates infected files during the scan, but the final report shows zero threats detected. The computer continues to experience web page freezing.

Before you start

Ensure your computer is connected to the internet to download the latest malware definitions, and close any active web browsers to prevent interference during the scan.

Solution 1Recommended

Update Definitions and Rerun Microsoft Safety Scanner

Downloading the latest version of the scanner and updating your primary antivirus definitions helps accurately identify and rule out false positives.

Microsoft Safety Scanner is updated frequently. If you use an outdated version, it might flag files incorrectly. The tool is designed to flag suspicious files preliminarily during the scan and clear them if deeper analysis at the end of the scan proves they are safe.

Download the latest version

Visit the official Microsoft download page and download the current Microsoft Safety Scanner (msert.exe), as the tool automatically expires 10 days after downloading.

Update existing security tools

Open Microsoft Defender and Malwarebytes (if installed) and manually check for the latest threat intelligence and virus definitions updates.

Run a full scan

Launch the newly downloaded Microsoft Safety Scanner, select 'Full scan', and wait for the process to complete without interrupting.

Review the scan log

Navigate to %SYSTEMROOT%\debug\msert.log (usually C:\Windows\debug\msert.log) and open it with Notepad to see detailed information about the scanned files and confirm why items were dismissed.

Update Definitions and Rerun Microsoft Safety Scanner

Understanding False Positives: The infection counter going up during a scan and dropping to zero at the end is a known behavior. The scanner flags heuristics temporarily and clears them if the final cloud check determines they are benign.

Solution 2

Troubleshoot Web Page Freezing Issues

If malware is not the cause, freezing web pages are likely due to browser issues, corrupted cache, or system performance bottlenecks.

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Frequently Asked Questions

Why does Microsoft Safety Scanner show files infected during the scan but zero at the end?

During the scan, the tool flags suspicious files based on preliminary matching. At the very end of the scan, it compares these flagged files against updated definitions in a deeper analysis. If they are deemed safe, they are marked as false positives, resulting in a final count of zero threats.

Where can I find the Microsoft Safety Scanner log file?

You can view the detailed scan results by opening the log file located at C:\Windows\debug\msert.log. You can open this file using Notepad or any standard text editor to see exactly which files were scanned and flagged.

Do I need to uninstall Microsoft Safety Scanner after using it?

No installation is required. Microsoft Safety Scanner is a portable executable. To remove it from your computer, simply delete the downloaded msert.exe file. Note that the tool expires 10 days after downloading, so you must download a fresh copy for future scans.

Can Microsoft Safety Scanner replace Microsoft Defender?

No, the Safety Scanner is designed strictly as an on-demand scanning tool to find and remove malware. It does not provide real-time protection, firewall features, or automatic updates like Microsoft Defender or Malwarebytes.

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