This article will help you to transfer Firefox or Thunderbird from one PC to another or just help you to create a backup of these software.

To create a backup, you need to download and install MozBackup utility: http://mozbackup.jasnapaka.com/

Then, Install and run it and follow the next steps:

Choose the action you want to make:

If you want to transfer profile on another PC or to restore it, on step #2 choose "restore" and then choose a backup file.

If you have a username and password that has changed, but Firefox keeps trying to automatically fill in old passwords for you? Delete them with these steps.

1. In Firefox click Tools > Options.

2. Click Security at the top.

3. Click the Show Passwords button.

4. Find the web site you wish to remove in the list. Click/highlight it with your mouse.

5. Click Remove and click Close then OK when you are finished.

Now the stored password will be removed from Firefox.

Solution applies to Windows.

1. Open My Computer.
2. Open following location C:\Documents and Settings\<user name>\
3. Open the Tools menu and click Options.
4. Click the View tab and ensure Show hidden files and folders is selected in the Advanced settings: section. Click OK to close the panel. 
5. A folder called Application Data should be visible. Open it.
6. Open the Phoenix folder.
7. Open the Profiles folder. 
8. Open the folder called "default". (If you are using another Firefox profile, open the folder matching the name of the Firefox profile you are using.) 
9. Open the folder whose name contains a strange sequence of characters and a .slt extension.
10. Find the chrome folder.
11. Rename the chrome folder to something else, like chrome-backup. 
12. Close the Explorer window and try and launch Firefox again.

If after this you get the same error, uninstall Firefox completely, and remove the folder you installed it into (e.g. C:\Program Files\Mozilla Firefox) completely, then reinstall Firefox.

When attempting to download and save a file in the browser, you may see an error message similar to the following:

File could not be saved, because the source file could not be read. Try again later, or contact the server administrator. 

This error can occur if the connection to the server was interrupted during the download. Make sure you are connected to the internet, then try the download again. If the problem persists, try these other solutions:

This error can occur after pausing and then resuming a download. Try downloading large files in a single step, without pausing. (It is possible that your security software is scanning and locking the file, which may still be in the system temporary folder after you pause the download. If Firefox can't access the file then resuming the download will fail.) 

If you are using a Firefox extension to manage your downloads, try disabling the extension via "Tools -> Add-ons -> Extensions". 

Another possible solution is to close Firefox completely and delete the "compreg.dat" file from the Firefox profile folder (for Windows Vista or 7: In the "Start Search" or "Search programs and files" box, type in:  %APPDATA%\Mozilla\Firefox\Profiles). 

Although Firefox enjoys the largest market share in the web browser industry, Internet Explorer is still a very popular browser for many users. Unfortunately, it can be difficult to make Windows 7 understand that you want Firefox to be the default browser on your PC.

Whether the cause us a plug-in, a glitch, or some unknown reason, some people experience a problem with setting Firefox as a computer’s default browser. Each time they restart Windows 7, Internet Explorer becomes the default browser no matter how many times these people set Firefox as the default. Learn how to force Windows 7 to permanently accept Firefox as the default web browser.
Set Firefox as Default Browser

If you constantly have to reset Firefox as the default browser, this trick will deny your computer access to Internet Explorer so that your PC will have to use Firefox when you click on a link. This method of setting Firefox as the default browser is a last resort fix. If this trick doesn’t work for you, you may have to uninstall IE altogether.

Log in to Windows 7 using an account with administrative privileges. Click on Start and type Default into the Search Programs and Files search box.

Press Enter and Windows 7 will open up the Default Programs options window. Click on the link titled Set Program Access and Computer Defaults.

In the Computer Defaults option window, click on the Custom option and Windows 7 will show you a list of options for program defaults.

Look for a set of options titled Choose a Default Web Browser. Normally, you should have the Use My Current Web Browser option chosen. This means that the browsers will decide using their own options which one is the default browser. Here, you will override the options of the browsers themselves and force Windows 7 to accept Firefox as the default browser at the administrative level.

Click the option titled Mozilla Firefox and make sure the option next to it titled Enable Access to this Program is checked. Now uncheck the option next to Internet Explorer titled Enable Access to this Program. This will force Windows 7 to ignore whether or not IE is set as the default browser at the software level.

Click OK, restart your computer, and see which browser Windows 7 recognizes as the default. You may want to run through the steps above again just to make sure that the options you chose are still the same.

At worst, you may have to uninstall IE in order to avoid having it set as the default web browser on your computer. At best, this trick will work but you will have to run through the steps above to undo this change should you want to start using IE again.

Unfortunately, this means that your computer will operate as if IE were not installed on the computer. This trick doesn’t work for everyone but it can be a last resort fix when IE keeps overriding Firefox as the default browser.

To remove Yahoo! toolbar, follow this steps:

1. Click the Tools menu in Firefox browser;

2. Choose Add-ons from drop down menu;

3. In extensions tab find and select Yahoo! toolbar.

4. Press Uninstall.

5. Press Uninstall again when you will be prompted.

6. Restart Firefox to apply  

If you’re a big Firefox fan, you probably noticed that whenever you open a new tab by clicking on the + icon or by press Ctrl + T, the page is always completely blank. There is absolutely nothing in the new tab!

Previously, I wrote about how you can fill that empty space in Firefox with the Speed Dial add-on, which is designed to let you access your favorite websites quickly. It gives you a grid layout similar to how Google Chrome shows you the most popular sites you visit in a new tab.

Another great add-on that makes use of all that empty space is NewTabURL (https://addons.mozilla.org/en-US/firefox/addon/2221). It’s specifically designed to set a default URL when new tabs are opened. So instead of a blank page, you can display a web page.

Once you download and install the add-on, restart Firefox. Now go to Tools and then Add-ons.

Now scroll down until you see NewTabURL and click on it. Then click on the Options button.

Here you can set the options for the new tab. You can choose from Blank page, Home page, Current page, or a custom URL.

What’s really cool about this add-on, however, is the fact that you can open a URL if it’s been copied to the clipboard. So let’s say you are in a Word document and there is a web link. Just copy it and then open a new tab in Firefox! It will open that URL.

If you are browsing the web, you can just right-click on a link and choose Copy link address. Then just open a new tab in Firefox. This is not that fabulous because you could just right-click and choose Open in new tab, but it’s still useful.

There are not any other options for this add-on, but if you want to use your new tab page to be something other than blank, this is a good option!

You can now specify multiple home pages in Mozilla Firefox. A home page is the site your browser visits when opened. The default home page for firefox is a nice and simple google search.

What if you have more than one pages that you’d like to open when firefox is launched? First, you need to open new tabs with webpages you’d like to set as the default home pages and go to Tools → Options.

Now you can see the buttons have changed from Use Current Page to Use Current Pages. Click on the Use Current Pages, and you will see the URLs you opened separated by pipe character.

You can also setup multiple home in Firefox without opening the pages by typing the URL manually.

If you want Yahoo! and Google as home pages, type:

http://www.yahoo.com/|http://www.google.com/

You can also set multiple homepages by using the Use Bookmark.. button. Save the pages you want to set as homepage into a dedicated bookmark folder and use that folder as Home Pages.