Could you dig down into your Firefox data and see whether the folders exist or are getting removed? This is on a hidden path, so you may first want to switch Windows to showing hidden files and folders:

http://windows.microsoft.com/en-us/windows/show-hidden-files

Then look for:

C:\Users\username\AppData\Roaming\Mozilla\Firefox

as a shortcut, you should be able launch that folder by pasting this into the Windows system search box and pressing Enter:

%APPDATA%\Mozilla\Firefox

In that Firefox folder, you should find (among other things):

(1) A Profiles folder (2) A profiles.ini file*

The profiles.ini file stores the names of profiles you created in the profile manager.

Those profiles should actually exist in the Profiles folder. If you compare, can you see what the issue is? For example, individual profile folders are missing or the profiles you've been creating are not listed in profiles.ini.

If the whole folder seems to be hopelessly haunted, I suggest renaming the Firefox folder to OldFox and the next time you run Firefox, it should create a default profile and a new profiles.ini file.

* .ini is one of the file extensions Windows normally hides. To more easily confirm full file names, you can set Windows to show all file extensions. See: http://windows.microsoft.com/en-us/windows/show-hide-file-name-extensions

Thanks. I finally got it. The profiles.ini file somehow got moved outside the profiles folder. Once I placed it back in everything started working again!

The profiles.ini file is normally in the Firefox folder. Maybe moving it caused Firefox to wake up and generate a working one.