Please do the following to ensure a clean installation.

1. Go to Download Firefox 4.0.1 and download the installation file to your desktop.
   
   
2. Then go to Add/Remove Programs, scroll down to "Mozilla Firefox" and remove it, choosing to keep your bookmarks, customizations etc., (don't checkmark the box).
   
   
3. Then reboot and delete the folder called "Mozilla Firefox" at this location: C:\Program Files\Mozilla Firefox
   
   
4. Finally run the installation file you downloaded to the desktop earlier.
   

Your bookmarks, customizations etc., are maintained in a different location and will become available to you again once you complete the installation.

After you complete the installation, please go to the Plugins Check page and update where necessary.

To Xrical;

Have followed these instructions exactly, with the same end result, except for one. In the previouse 6 attempts, the Mozilla program folder was present in the program files folder when I went there to delete it. This last attempt (the 7th), after un-installing Firefox from Add/Remove programs and a re-boot, there was no Mozilla folder present to delete. Any other suggestions?

Could you please go to this site: http://www.enhanceie.com/ua.aspx

Then in the paragraph called "Your browser sent the following headers" copy the User Agent which is displayed in the red font and then come back to your thread here and paste it into your next post please.

Also, I'm a little bit confused because you wrote: "This application has failed to start because sqlite.dll was not found". However, there's no file by that name in Firefox. Could you check the error message again please?

User-Agent: Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0; .NET CLR 2.0.50727; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729)

Attaching 2 jpeg images of the pop-up messages generated when attempting to open Firefox.

> > > I'm looking over the pictures I posted, and Firefox.exe would be the installer, methinks - would it not? The browser, after it is installed would not carry the .exe suffix, would it?

Now I'm confused.

The only thing your user agent reveals is that you're using IE8 to post your messages which doesn't help at all.

But one thing confuses me with the error message you posted in the image showing that firefox.exe couldn't find sqlite3.dll. It looks to me like you were using Windows 2000 when you took the picture because in the second one, the appearance of the title bar has changed to Windows XP style (?).

Could you try doing the following please.

1. Download version 3.6.17 from here: Download Firefox v3.6.17
   
   
2. Follow the same procedure to uninstall/install it as in my initial post. This will install the sqlite3.dll file which appears to have been removed in 4.0.x
   
   
3. When the installation terminates, click Help | Check For Updates and try and update to 4.0.1 that way.

Installing 3.6.17 has solved the .dll issue. Thank you for your assistance and insights.

You're welcome.

Have a simular problem where spoolsv doesn't start because mozqlite3.dll is missing, have gone back to version 3 which solves the problem but as soon as I insall version 4 the problem reappears.

User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0.1) Gecko/20100101 Firefox/4.0.1