Nope. I don't have that tab at all. This is the first I've ever seen it.
What a mystery.
I keep calling it a “tab” because in years past, an icon or device at the edge of a file or folder, was a tab; but I guess now with the advent of TABS *within* Internet browser windows, some call the orange-ish thing a “button.”
Given the problems reported on this FR page, I would un-install all Mozilla software, and follow that by running a cache cleaner, and follow that with a restart of the computer.
After which, I’d run a Registry cleaner; and, probably use that Registry utility’s feature to search for “Mozilla” and “Firefox” in the Registry ... to see if anything looks obviously as though it should have been cleaned out ... and make note of that.
Then, another restart, and after *that,* install a fresh copy of Mozilla Firefox, via the FTP source:
ftp://ftp.mozilla.org/pub/mozilla.org/firefox/releases/
(Navigate to find Firefox 27.0.1, the installer, and download it -— also getting the md5 or sha1 checksum and verify the downloaded file “Firefox Setup 27.0.1.exe”.)
Install it.
Check to see if your “menu toolbar” is checked. It’s the toolbar that says File Edit View History, etc across the top. If you uncheck that toolbar, the Firefox orange rectangle will appear at the upper left.