What is stmain.dll?

Stmain.dll is a browser extension for Internet Explorer. This add-on enables several additional functions for Internet Explorer. You can disable it through the Extras menu (key combination Alt + X) under Manage Add-ons. The following paragraph provides more information about MSN Search Toolbar.

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Stmain.dll file information

The process known as st or Windows Live Toolbar Search Toolbar Helper belongs to software st or Windows Live Toolbar or Brain Trainer (version 2) or iTunes by Microsoft (

Description: Stmain.dll is not essential for Windows and will often cause problems. Stmain.dll is located in a subfolder of "C:\Program Files"—generally C:\Program Files\MSN Apps\ST\01.02.3000.1002\en-xu\. Known file sizes on Windows 10/8/7/XP are 155,648 bytes (99% of all occurrences), 143,360 bytes or 141,824 bytes. 
This .dll file is a Browser Helper Object (BHO) that runs automatically every time you start your web browser. BHOs are not stopped by personal firewalls, because they are identified by the firewall as part of the browser itself. BHOs are often used by adware and spyware. IDs used by this BHO include 9394EDE7-C8B5-483E-8773-474BF36AF6E4. The program has no visible window. The stmain.dll file is able to monitor web browsers. There is no detailed description of this service. Stmain.dll is not a Windows system file. There is no information about the author of the file. Stmain.dll is able to record keyboard and mouse inputs. Therefore the technical security rating is 76% dangerous, however you should also read the user reviews.

Uninstalling this variant: You could uninstall the software Windows Live Toolbar or iTunes using the Uninstall a Program function of Windows Control Panel (Windows: Start, Settings, Control Panel, Uninstall a Program).

Recommended: Identify stmain.dll related errors

External information from Tony Klein:

Important: Some malware camouflages itself as stmain.dll. Therefore, you should check the stmain.dll process on your PC to see if it is a threat. If MSN Search Toolbar has changed your browser's search engine and start page, you can recover your browser's default settings as follows:

Reset default browser settings for Internet-Explorer ▾
  1. In Internet Explorer, press the key combination Alt + X to open the Tools menu.
  2. Click Internet options.
  3. Click the Advanced tab.
  4. Click the Reset... button.
  5. Enable the Delete personal settings option.
This will reset your Internet Explorer to its default settings. Your browser will start with the familiar start page and search engine—without popups, ads, cookies, but all browser add-ons are deleted too [1]. Make cleaning up your browser and your computer simpler and safer with Security Task Manager.


User Comments

it keeps popping up when i open my yahoo mail
  michael sweeney  
Explorer Extension for Microsoft Messenger (Microsoft Network)
  Asier Larrabide  
como recuperar stmain dll
First of all its related to MSN tool bar and second it is certified by Microsoft which is trustable corporation ..of course it is bound by all the reuqired laws for internet and customer saftey
  Vishal Patel  
on my system just closes some web but, when you need that web you take care about it
  Douglas Camacho   (further information)
uses high resource and show to be IE browser extension as well as a vebatum activity logger
  ARClark-Steiner   (further information)
causes crahes ie while attemting to run java applications
Uninstall MSN toobar
More comments can be found here:
    (further information)

Rating chart

Summary: Average user rating of stmain.dll: based on 73 votes with 9 reviews. 25 users think stmain.dll is essential for Windows or an installed application. 4 users think it's probably harmless. 19 users think it's neither essential nor dangerous. 11 users suspect danger. 14 users think stmain.dll is dangerous and recommend removing it. 7 users don't grade stmain.dll ("not sure about it").

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Best practices for resolving stmain issues

The following programs have also been shown useful for a deeper analysis: ASecurity Task Manager examines the active stmain process on your computer and clearly tells you what it is doing. Malwarebytes' well-known Banti-malware tool tells you if the stmain.dll on your computer displays annoying ads, slowing it down. This type of unwanted adware program is not considered by some antivirus software to be a virus and is therefore not marked for cleanup.

A clean and tidy computer is the key requirement for avoiding PC trouble. 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.

Other processes

stmain.dll [all]