What is mstDfrgS.exe?

The .exe extension on a filename indicates an executable file. Executable files may, in some cases, harm your computer. Therefore, please read below to decide for yourself whether the mstDfrgS.exe on your computer is a Trojan that you should remove, or whether it is a file belonging to the Windows operating system or to a trusted application.

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MstDfrgS.exe file information

The process known as mstDefrag Service belongs to software mst Defrag Home Edition or mst Defrag Workstation Edition by mst software GmbH, Germany ( or mst software, Martin Stiemerling, Germany (

Description: MstDfrgS.exe is not essential for the Windows OS and causes relatively few problems. The file mstDfrgS.exe is located in a subfolder of "C:\Program Files". The file size on Windows 10/8/7/XP is 589,824 bytes. 
There is an icon for this program on the taskbar next to the clock. You can uninstall this program in the Control Panel. It is not a Windows system file. MstDfrgS.exe is able to connect to the Internet and monitor applications. Therefore the technical security rating is 15% dangerous; however you should also read the user reviews.

Uninstalling this variant: If you are having problems with mstDfrgS.exe, you can also safely remove the program using the uninstall program of mst Defrag Home Edition or mst Defrag Workstation Edition (Control Panel ⇒ Uninstall a Program).

Recommended: Identify mstDfrgS.exe related errors

Important: Some malware camouflages itself as mstDfrgS.exe, particularly when located in the C:\Windows or C:\Windows\System32 folder. Therefore, you should check the mstDfrgS.exe process on your PC to see if it is a threat. We recommend Security Task Manager for verifying your computer's security. This was one of the Top Download Picks of The Washington Post and PC World.


User Comments

HD defrag soft knock's spots off MS own defrag tool.
In der Freeware Option sehr gut, da es hier keine Internet-Verbindung aufbaut, die bei einer Defrag-Software überflüssiger als schlüssig ist. Dennoch dann zu empfehlen, wenn man den Windows Eigenen Defragmentieren als Lausch-Angriffsziel und Überwachungsorgan auschalten will. Man sollte es sofort tun ! Dieser Defrag ist dann emfehlenswert wenn man wiedermal die Firewall so konfiguriert, das der Eigene ! aufgebaute Verbindungskanal zum Internet völlig deaktiviert wird. Funktioniert dann nämlich trotzdem hervorragend.
  Hamburger Jung.  
autodefragmenter (top tool)

Summary: Average user rating of mstDfrgS.exe: based on 5 votes with 4 user comments. 3 users think mstDfrgS.exe is essential for Windows or an installed application. One user thinks it's neither essential nor dangerous. One user thinks mstDfrgS.exe is dangerous and recommends removing it.

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Best practices for resolving mstDfrgS issues

A clean and tidy computer is the key requirement for avoiding problems with mstDfrgS. This means running a scan for malware, cleaning your hard drive using cleanmgr and sfc /scannow, uninstalling programs that you no longer need, checking for Autostart programs (using msconfig) and enabling Windows' Automatic Update. Always remember to perform periodic backups, or at least to set restore points.

Should you experience an actual problem, try to recall the last thing you did, or the last thing you installed before the problem appeared for the first time. Use the resmon command to identify the processes that are causing your problem. Even for serious problems, rather than reinstalling Windows, you are better off repairing of your installation or, for Windows 8 and later versions, executing the DISM.exe /Online /Cleanup-image /Restorehealth command. This allows you to repair the operating system without losing data.

To help you analyze the mstDfrgS.exe process on your computer, the following programs have proven to be helpful: Security Task Manager displays all running Windows tasks, including embedded hidden processes, such as keyboard and browser monitoring or Autostart entries. A unique security risk rating indicates the likelihood of the process being potential spyware, malware or a Trojan. Malwarebytes Anti-Malware detects and removes sleeping spyware, adware, Trojans, keyloggers, malware and trackers from your hard drive.

Other processes

mstDfrgS.exe [all]