Hi, try performing a Clean reinstall. This means you remove your Firefox program files and then reinstall Firefox. This process does not remove your Firefox profile data (such as bookmarks and passwords), since that information is stored in a different location.

To do a clean reinstall of Firefox, please follow these steps: Note: You might want to print these steps or view them in another browser.

1. Download the latest Desktop version of Firefox from mozilla.org (or choose the download for your operating system and language from this page) and save the setup file to your computer.
2. After the download finishes, close all Firefox windows (or open the Firefox menu and click the close button ).
3. Delete the Firefox installation folder, which is located in one of these locations, by default:
   • Windows:
     • C:\Program Files\Mozilla Firefox
     • C:\Program Files (x86)\Mozilla Firefox
   • Mac: Delete Firefox from the Applications folder.
   • Linux: If you installed Firefox with the distro-based package manager, you should use the same way to uninstall it - see Install Firefox on Linux. If you downloaded and installed the binary package from the Firefox download page, simply remove the folder firefox in your home directory.
4. Now, go ahead and reinstall Firefox:
   1. Double-click the downloaded installation file and go through the steps of the installation wizard.
   2. Once the wizard is finished, choose to directly open Firefox after clicking the Finish button.

More information about reinstalling Firefox can be found here.

WARNING: Do not use a third party uninstaller as part of this process. Doing so could permanently delete your Firefox profile data, including but not limited to, extensions, cache, cookies, bookmarks, personal settings and saved passwords. These cannot be easily recovered unless they have been backed up to an external device! See Back up and restore information in Firefox profiles.

Please report back to say if this helped you!

Thank you.

I have now made a complete reinstall of Firefox. I got the same message. It seems to be sent by LenovoFamilySecurity.exe-Programfel. Am surprised that after clicking OK,everything goes on and functions correct! Best regards! Appreciating your efforts! Sven Mellquist

If the problem is with LenovoFamilySecurity.exe then you should contact its support.

Try first to re-install/update the program.

Remove Lenovo Family Security from your system :
Windows Control Panel => Programs highlight the program and click 'Uninstall'

See :   http://www.shouldiremoveit.com/FamilySafetyGuide-92153-program.aspx

I have removed LenovoFamilySecurity from my pc and tried PCPurifier installed but they stop after a while. "could not change name". Do you have any suggestions? WBR/Sven

What message do you get now ? When is it that you get this message ? Please provide a screenshot of the message.

What stops after a while ? Does Firefox run most of the time and sometimes stop ?

What is PCpurifier ? How is that connected with this issue & Firefox ? If it is some sort of registry cleaning tool it may not be prudent to use that and may itself cause issues with use of your Windows computer.

Are you still able to use the Windows MS Edge browser OK without problems ?

I note you did apparently post this question from a Windows 10 machine using Firefox 53 is that the same machine as you have problems on or are you using a different one to post these questions.

PC Purifier (by www.pcpurifier.com) is a potentially unwanted program, which is advertised as a system optimizer, and once installed it claims that several issues were been detected on your computer. ... PC Purifier is bundled with other free software that you download off of the Internet. You need to remove this from your system : Windows Control Panel => Programs

As you have malware installed on your computer, you need to do a malware check :

• https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-caused-malware

Scan with all programs because each program detects different malware. All these programs have free versions.

• Malwarebytes' Anti-Malware: http://www.malwarebytes.org/mbam.php

• AdwCleaner: http://www.bleepingcomputer.com/download/adwcleaner/ http://www.softpedia.com/get/Antivirus/Removal-Tools/AdwCleaner.shtml

• SuperAntispyware: http://www.superantispyware.com/

• Microsoft Safety Scanner: http://www.microsoft.com/security/scanner/en-us/default.aspx

• Windows Defender: http://windows.microsoft.com/en-us/windows/using-defender

• Spybot Search & Destroy: http://www.safer-networking.org/en/index.html

Hei Happy112 ! I have deleted PCPurifier and made a malware check with all six programs, that you so kindly sent to me. Sorry to say, nothing changed. They found a bundle of durty issues and removed them. Is there anything more i can do? With best regards /Sven

A screenshot of the irritating message looks like this. (in swedish)

LVT.exe - programfel Det gick inte att starta programmet korrekt (0xc00000e5). Klicka på OK för att stänga programmet.

After clicking OK, Firefox runs normally. Sven

svemel2911 said

Sorry to say, nothing changed.

Bummer   !!! So you still get that same annoying error message, eh  ? I'm running out of ideas here, unless : Do you by any chance have Trusteer Rapport installed  ? Or something like Kaspersky, AVAST or Bitdefender  ? If so : would you ( for now ) disbale it/them and see if that makes a difference  ?

svemel2911 said

A screenshot of the irritating message looks like this. (in swedish) LVT.exe - programfel Det gick inte att starta programmet korrekt (0xc00000e5). Klicka på OK för att stänga programmet. After clicking OK, Firefox runs normally. Sven

Well, everything gets back to normal after you've clicked OK,   but still - this shouldn't happen. I am now hoping that maybe you have some anti-virus program installed that causes this, and that disabling it will solve the problem. Keeping my fingers crossed .......

LVT.exe is known as Lenovo Vantage Technology

How to remove LVT.exe If you encounter difficulties with LVT.exe , you can uninstall the associated program (Start > Control Panel > Add/Remove programs http://www.processchecker.com/file/LVT.exe.html

So what is LVT.exe possibly Lenovo Vantage Technology

If it is some bloatware added by the computer manufacturer it probably is difficult to disable or remove. I did find one of their support threads suggesting LVT should be kept

• https://forums.lenovo.com/t5/Lenovo-E-H-K-M-Q-Y-and-ErazerX/Which-programs-are-bloatware-on-H500S/m-p/1809104#M8072

I suspect you may just have to live with that. Or maybe consult one of the security fora we suggest in our article and see if they can advise and assist

• Troubleshoot Firefox issues caused by malware

  You can ask for help in a forum specializing in malware removal, such as those listed below:
  * Bleeping Computer Forums
  * Spyware Warrior Forums
  * SWI Forums

Remember the scandal a couple or so years back when it was discovered how dangerous the Superfish was that they shipped

• https://wikipedia.org/wiki/Superfish

  ... On February 20, 2015, the United States Department of Homeland Security advised uninstalling it and its associated root certificate, because they make computers vulnerable to serious cyberattacks, including interception of passwords and sensitive data being transmitted through browsers. ...

• Mozilla Security Blog: Getting Superfish out of Firefox https://blog.mozilla.org/security/2015/02/27/getting-superfish-out-of-firefox/
• TheRegister: Mozilla mulls Superfish torpedo http://www.theregister.co.uk/2015/02/23/mozilla_mulls_super_phish_torpedo/

Remove Lenovo Vantage Technology from your system, the same way you did with Lenovo Family Security : Windows Control Panel => Programs (just like FredMcD already suggested)

See :

http://www.shouldiremoveit.com/LVT-19960-program.aspx

FredMcD said

LVT.exe is known as Lenovo Vantage Technology How to remove LVT.exe If you encounter difficulties with LVT.exe , you can uninstall the associated program (Start > Control Panel > Add/Remove programs http://www.processchecker.com/file/LVT.exe.html

Good for you to spot that, Fred   !

Whenever I see something I don't know, I do a web search to find out what it is.

svemel2911 said

A screenshot of the irritating message looks like this. (in swedish)

LVT.exe - programfel
Det gick inte att starta programmet korrekt (0xc00000e5). Klicka på OK för att stänga programmet.

After clicking OK, Firefox runs normally. Sven

"LVT.exe - bug Could not start the program correctly"

This could be a problem with some Visual C++ libraries (SxS; side-by-side) that are missing or corrupted.

Microsoft Visual C++ Redistributable for Visual Studio 2017 https://www.visualstudio.com/downloads/ Download Microsoft Visual C++ 2015 Redistributable Update 3: https://www.microsoft.com/en-us/download/details.aspx?id=53840

dear cor-el! I followed your idea about Visual C and Visual Studio, without result. Question: my pc is a Lenovo machine.What happens if I remove via the control program all "Lenovo-programs"?

Programchecker is a practicl program. I liked it.

How do I do a Web search? I am an old amateur.

WBR/Sven

Advice, given by Lenovo :

Uninstall useless programs

By taking a quick look at the PC's Control Panel, you can quickly identify and remove any software programs that are rarely used. Go through this list with a fine-tooth comb, uninstalling any programs that you don't use often, but remembering to exercise caution when uninstalling programs that may be unfamiliar. Many computers will come with software and files pre-installed, but identifying which of these no longer serve a purpose can free up some storage space and boost performance. It is important to uninstall software correctly, as merely deleting a folder or shortcut leaves unwanted files on the computer.

See : http://www3.lenovo.com/us/en/faqs/laptop-faqs/how-to-speed-up-your-computer/

Hallo! I have been silent, because the problem has disappeared! I have tried all that you all recommended, but dont know what really worked. Anyhow I would like to thank you for your performances! Best regards! Sven Mellquist

Hello again Sven , Thanks for posting back to say the issue is solved now.

svemel2911 said

... How do I do a Web search? I am an old amateur. WBR/Sven

A web search is simply searching for information on the internet. You may use Firefox to do that. Use Firefox's search bar or the search bar on the new tab page or the default home page.

Here are some of our help articles that you or other readers of this thread may find of interest.

• Get started with Firefox - An overview of the main features
  • _{Get started with Firefox - An overview of the main features}_search-the-web
• Search with the Firefox Address Bar
  • Change your default search settings in Firefox
  • (Wikipedia: Search Engines more detail )
• Use popular search suggestions in the Firefox Search bar
• Address bar autocomplete suggestions in Firefox
• The new tab page also has a search bar by default Customize your Firefox New Tab page & New Tab page in Firefox
• At present there is even an addon that lets you use different search engines in the different Firefox search methods
  Keyword search addon ([change the] Search in the address bar without changing your search engine. )