Hmm, I'm not sure what you mean by a blank canvas, but maybe...

Firefox 33.0 was incompatible with some older graphics card/chipset drivers. (This may be fixed for your system by Firefox 33.0.1, but that's a very recent release and I haven't seen a lot of feedback on it yet.)

The temporary workaround is to disable hardware acceleration (you can do this now before upgrading) and the longer-term solution is to update your graphics card/chipset drivers.

More info: FireFox launches a black screen after 33 update (scroll down for links to update Intel software)

I was maybe a bit unclear, Firefox launches an empty profile without bookmarks or extensions after I've copy pasted my old data in the new profile.

Hmm, you should see personal data in the profile if everything dropped into its correct place. Can you try it a different way?

First, make sure Firefox is fully closed. Then go ahead and open these two folders:

(1) Old Firefox Data

(2) Your Firefox profiles folder. To most quickly get to this file, you can type or paste the following in the Start menu search box (and press Enter) or in the address bar of a Windows Explorer window:

%APPDATA%\Mozilla\Firefox\Profiles

Next, copy your earlier profile folder from #1 to #2 (e.g., right-click>Copy from #1 and right-click>Paste to #2).

In window #1, type or paste this in the address bar and press Enter:

%APPDATA%\Mozilla\Firefox

In this folder you should see a file named profiles.ini. If Windows is hiding the .ini extension you may want to unhide it. See this Microsoft article on steps for that: http://windows.microsoft.com/en-us/windows/show-hide-file-name-extensions

Right-click>Edit the profiles.ini file and it should open in Notepad. You should see something like the following:

[General]
StartWithLastProfile=1

[Profile0]
Name=default
IsRelative=1
Path=Profiles/asdf1234.default
Default=1

There may be multiple entries, but you want to modify the one that is currently the default and dysfunctional.

Change the part of Path after Profiles/ to match the name of the folder you pasted into window #2. Then try starting Firefox again

Note that Firefox uses two location for the Firefox profile folder, the main profile in AppData\Roaming and the caches in AppData\Local, so make sure to copy the files to the correct location.

You can use this button to go to the currently used Firefox profile folder:

• Help > Troubleshooting Information > Profile Directory: Show Folder (Linux: Open Directory; Mac: Show in Finder)

Thanks a lot for your time spent answering my question.

I had already done this two steps though, opening my profiles folder and copy pasting the exact content, then selecting the default profile using firefox.exe -p. The newly selected profile still doesn't load any of the content in the folder.

I also realized that Firefox switched to French (my Live account's language), even if my system is in English (win 8.1) and it used to be in English. The created user ("Utilisateur par défaut") includes two spaces and one special character, could it have an influence on this? Is there a log to check the loading of the new profile?

Hi fanfouay, the reason I gave you a different procedure -- copying the actual folder and then editing profiles.ini -- is because copying the contents of the folder was not working for you.