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Starting Firefox gives a webpage warning of a Windows Server error and virus problem

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  • 8 have this problem
  • 16 views
  • Last reply by JPaulV

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When starting Firefox I get a webpage with warnings about Microsoft Server and calling some number to get assistance. My installed virus software cannot find any problem but why is Firefox being hijacked? What can I do to put an end to this?

When starting Firefox I get a webpage with warnings about Microsoft Server and calling some number to get assistance. My installed virus software cannot find any problem but why is Firefox being hijacked? What can I do to put an end to this?

Chosen solution

Does this appear instead of your home page, or in addition, or is it a message designed to appear like one that Firefox might generate?

If your home page is set correctly but you get a different page when using your desktop shortcut / pinned taskbar icon, the shortcut itself may have the hijack. To check for that, either:

  • Desktop shortcut: right-click the icon, choose Properties
  • Pinned taskbar icon: right-click the icon, right-click Mozilla Firefox, choose Properties

Windows normally will select the Shortcut tab. If not, go ahead and click the Shortcut tab.

The Target line should not have anything after this part:

  • 32-bit Firefox on 64-bit Windows: "C:\Program Files (x86)\Mozilla Firefox\firefox.exe"
  • Otherwise: "C:\Program Files\Mozilla Firefox\firefox.exe"

If anything is listed after that, clear it out and save your change. To test, you can either:

  • Desktop shortcut: double-click the icon to launch a new window
  • Pinned taskbar icon: right-click the icon, click Mozilla Firefox to launch a new window

If you get your home page, it worked.

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Chosen Solution

Does this appear instead of your home page, or in addition, or is it a message designed to appear like one that Firefox might generate?

If your home page is set correctly but you get a different page when using your desktop shortcut / pinned taskbar icon, the shortcut itself may have the hijack. To check for that, either:

  • Desktop shortcut: right-click the icon, choose Properties
  • Pinned taskbar icon: right-click the icon, right-click Mozilla Firefox, choose Properties

Windows normally will select the Shortcut tab. If not, go ahead and click the Shortcut tab.

The Target line should not have anything after this part:

  • 32-bit Firefox on 64-bit Windows: "C:\Program Files (x86)\Mozilla Firefox\firefox.exe"
  • Otherwise: "C:\Program Files\Mozilla Firefox\firefox.exe"

If anything is listed after that, clear it out and save your change. To test, you can either:

  • Desktop shortcut: double-click the icon to launch a new window
  • Pinned taskbar icon: right-click the icon, click Mozilla Firefox to launch a new window

If you get your home page, it worked.

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If it isn't that, here's my is my suggested procedure for tracking down and cleaning up bad add-ons and other hijackers. I know it seems long, but it's really not that bad.

(For Windows Vista, 7, 8, 8.1, 10; XP is somewhat different)

(1) Open the Windows Control Panel, Uninstall a Program. After the list loads, click the "Installed on" column heading to group the infections, I mean, additions, by date. This can help in smoking out undisclosed bundle items that snuck in with some software you agreed to install. Be suspicious of everything you do not recognize/remember, as malware often uses important or innocent sounding names to discourage you from removing it. Take out as much trash as possible here.

(2) Open Firefox's Add-ons page using either:

  • Ctrl+Shift+a
  • "3-bar" menu button (or Tools menu) > Add-ons
  • in the Windows "Run" dialog, type or paste
    firefox.exe "about:addons"

In the left column, click Plugins. Set nonessential and unrecognized plugins to "Never Activate".

In the left column, click Extensions. Then, if in doubt, disable (or Remove, if possible) unrecognized and unwanted extensions. All extensions are optional; none come with Firefox.

Often a link will appear above at least one disabled extension to restart Firefox. You can complete your work on the tab and click one of the links as the last step.

Any improvement?

(3) You can search for remaining issues with the scanning/cleaning tools listed in our support article: Troubleshoot Firefox issues caused by malware. These on-demand scanners are free and take considerable time to run. If they finish quickly and especially if they require payment, you may have a serious infection. I suggest the specialized forums listed in the article in that case.

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Thank you for the solution. When I did as you suggested I found that there was an additional string of characters after the link to "firefox.exe". I deleted and saved. When I started Firefox I got back my original homepage.

Thank you. I also saved the rest of your suggestions and I will refer to it in the future. I am not sure if the image attached in the original post so let me try to attach it here.

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Wow, I wonder how that got on your system! Hopefully you won't see it again.

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I am again having the same problem I had previously but there is no change in the Firefox address on my computer, so that is not the problem. See the attached screenshots. The Microsoft toll free number I see is never the same and the URL is not for Microsoft so this must be some kind of malware. Problem is no anti-virus program seems able to detect it.

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Does it make any difference if you start up in Firefox's Safe Mode?

In Safe Mode, Firefox temporarily deactivates extensions, hardware acceleration, and some other advanced features to help you assess whether these are causing the problem.

If Firefox is not running: Hold down the Shift key when starting Firefox.

If Firefox is running: You can restart Firefox in Safe Mode using either:

  • "3-bar" menu button > "?" button > Restart with Add-ons Disabled
  • Help menu > Restart with Add-ons Disabled

and OK the restart.

Both scenarios: A small dialog should appear. Click "Start in Safe Mode" (not Refresh).

Any improvement? (More info: Diagnose Firefox issues using Troubleshoot Mode)

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I get it in Safe Mode also.

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From time to time, we learn about a program folder infection. To address that possibility:

Clean Reinstall

We use this name, but it's not about removing your settings, it's about making sure the program files are clean (no inconsistent or alien code files). As described below, this process does not disturb your existing settings. Do NOT uninstall Firefox, that's not needed.

(A) Download a fresh installer for Firefox 47.0 from https://www.mozilla.org/firefox/all/ to a convenient location. (Scroll down to your preferred language.) For maximum plugin compatibility, choose the 32-bit version.

(B) Exit out of Firefox (if applicable).

(C) Using Windows Explorer/My Computer, rename the program folder as follows:

C:\Program Files (x86)\Mozilla Firefox

to

C:\Program Files (x86)\OldFirefox

(D) Run the installer you downloaded in step (A). It should automatically connect to your existing settings.

Note: Some plugins may exist only in that OldFirefox folder. If something essential is missing, look in these folders:

  • \OldFirefox\Plugins
  • \OldFirefox\browser\plugins

Hopefully the new install will be (and stay) clean. Any improvement?

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I did something similar to what you suggested, except I uninstalled Firefox completely and cleaned the registry too. I reinstalled using Firefox 47.0 and soon after starting Firefox one of the windows/tabs that I opened (New Tab) opened the Microsoft Warning Window (Windows+Warning+Again).

I wonder if this is something Microsoft is deliberately doing to those computers that have been set to not accept any Windows 10 updates? I do not have this problem on my other laptop only on my Dell M6800 Workstation. It is set to not accept any Windows 10 updates that would change the Windows 7 Ultimate OS.

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That's not a real Microsoft page. It's coded into the address bar and undoubtedly leads somewhere very bad.

I'm not sure whether the uninstall you did had the effect of removing the Firefox program folders.

Anyway, it seems your home page is driving you to this unwanted page, or your system is infected.

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If my system is infected then there doesn't seem to be any program that can detect the virus or malware.

I think I am going to uninstall Firefox and simply stop using it.

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Okay, I think this thread has nearly all the things I would suggest for "self-help." If it's not (1) your home page, (2) a problem with your shortcut, (3) external malware, (4) a bad add-on, or (5) an infected program folder, it's hard to think of what could be triggering this address to load.

Some much less likely thoughts:

(1) You could check for a connection hijack. You can review your Firefox connection settings here:

"3-bar" menu button (or Tools menu) > Options

In the left column, click Advanced, then on the right side select the Network mini-tab at the top. Click the "Settings" button.

The default of "Use system proxy settings" piggybacks on your Windows/IE "LAN" settings, but you could try "No proxy" to see whether that works better.

(2) Occasionally users find unwanted actions in their Windows Task Scheduler, but I don't know whether a scheduled task can hijack your start page.


If you decide to come back to Firefox, could you try this experiment:

Create a new Firefox profile

A new profile will have your system-installed plugins (e.g., Flash) and extensions (e.g., security suite toolbars), but no themes, other extensions, or other customizations. It also should have completely fresh settings databases and a fresh cache folder.

Exit Firefox and start up in the Profile Manager using the Start menu > search box (or Run) -- type or paste the following and press Enter to run it:

firefox.exe -P

Don't delete anything here!

Any time you want to switch profiles, exit Firefox and return to this dialog.

Click the Create Profile button, assign a name like June2016, and skip the option to relocate the profile folder. After creating the profile, select it and start Firefox in that profile.

Do you get the built-in Firefox home page or the hijack page?

When returning to the Profile Manager, you might be tempted to use the Delete Profile button. But... it's a bit too easy to accidentally delete your "real" profile, so I recommend resisting the temptation. If you do want to clean up later, I suggest making a backup of all your profiles first in case something were to go wrong.

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I used Malwarebytes and removed two malware infections. Now if I can eliminate the constant redirection to websites I do not want, I will be all set.