What is shellext.dll?

Shellext.dll is a Windows DLL file. DLL is the abbreviation for Dynamic Link Library. DLL files are needed by programs or web browser extensions, because they contain program code, data, and resources. The following information can help you determine if shellext.dll is a Windows system file or if it belongs to an application that you can trust.

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Shellext.dll file information

The process known as Microsoft Security Client Shell Extension or Shell Extension or ShellExt Dynamic Link Library or Advanced System Optimizer or Microsoft Security Essentials Shell Extension or TextPad shell extension DLL or Agent Ransack Shell Extensions or Power MP3 WMA Converter Shell Extension

belongs to software Microsoft Security Client or Ad-Aware or ESET Smart Security or Microsoft Security Essentials or ESET NOD32 Antivirus or HP CloudDrive or Advanced System Optimizer or Shell Extension

by Microsoft ( or Lavasoft AB ( or ESET ( or Versionate or Systweak ( or Tomasz Pawlak or Axantum Software AB ( or Helios Software Solutions (

Description: Shellext.dll is not essential for the Windows OS and causes relatively few problems. The shellext.dll file is located in a subfolder of "C:\Program Files". Known file sizes on Windows 10/8/7/XP are 301,128 bytes (9% of all occurrences), 169,216 bytes and 43 more variants. 
A .dll file (Dynamic Link Library) is a special type of Windows program containing functions that other programs can call. This .dll file can be injected to all running processes and can change or manipulate their behavior. The program is not visible. Shellext.dll is not a Windows system file. There is no detailed description of this service. It can change the behavior of other programs or manipulate other programs. It is digitally signed. The software can be uninstalled in the Control Panel. Shellext.dll is able to monitor applications and hide itself. Therefore the technical security rating is 48% dangerous, however you should also read the user reviews.

Uninstalling this variant: In case of any problems with shellext.dll, you may want to do the following:
  1) uninstall the associated program (Start > Control Panel > Uninstall a Program > Microsoft Security Client or Ad-Aware)
  2) search the support area on the Microsoft website.

Recommended: Identify shellext.dll related errors

If shellext.dll is located in the C:\Windows folder, the security rating is 82% dangerous. The file size is 184,832 bytes. There is no description of the program. It can change the behavior of other programs or manipulate other programs. The program is not visible. The service has no detailed description. It is not a Windows system file.

Important: Some malware camouflages itself as shellext.dll, particularly when located in the C:\Windows or C:\Windows\System32 folder, for example Rogue:Win32/FakeRemoc (detected by Microsoft), and WinAntiSpyware (detected by Symantec). Therefore, you should check the shellext.dll 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

Textpad Shell Extension
  SSigurdarson   (further information)
Text editor.
  Ben!   (further information)
system optimiser - still present even after software uninstallation
Textpad Shell Extension
hidden in common files aol. Startup entry says 6 months of aol included although this is a browser helper object.
  Jacob Steelsmith  
This file is installed as part of a program called "Advanced System Optimizer" it appears to be for adding the programs commands to the os context menus. Annoying to get rid of. Boot into safe mode and delete this file after you have uninstalled the software.
  Manchine   (further information)
included with BitBeamer FTP software (now discontinued)
its easy to remove just make a bat file that remove's the file and let it start when windows starts
  the swan  
Installs with Advanced System Optimizer and remains after uninstall
Inculded in NOD32 v3.1. It's not dangerous.
I unistalled advanced system pro and am left with it sittinas shelltxt.dll and I went to safe mode as administrater and I still can;t delete it in my programs
  Ruth Bradshaw  
Installed with Stardock Object Desktop

Rating chart

Summary: Average user rating of shellext.dll: based on 21 votes with 12 user comments. 13 users think shellext.dll is essential for Windows or an installed application. 6 users think it's neither essential nor dangerous. 2 users suspect danger. 2 users don't grade shellext.dll ("not sure about it").

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Best practices for resolving shellext issues

A clean and tidy computer is the key requirement for avoiding problems with shellext. This means running a scan for malware, cleaning your hard drive using 1cleanmgr and 2sfc /scannow, 3uninstalling programs that you no longer need, checking for Autostart programs (using 4msconfig) and enabling Windows' 5Automatic 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 6resmon 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 7DISM.exe /Online /Cleanup-image /Restorehealth command. This allows you to repair the operating system without losing data.

To help you analyze the shellext.dll process on your computer, the following programs have proven to be helpful: ASecurity 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. BMalwarebytes Anti-Malware detects and removes sleeping spyware, adware, Trojans, keyloggers, malware and trackers from your hard drive.

Other processes

shellext.dll [all]