Have you tried uninstalling it?
https://support.mozilla.com/en-US/kb/Uninstalling+add-ons#How_to_uninstall_extensions_and_themes

Thanks for the advice I wasnt able to uninstall the normal way because it only let me disable, uninstall was grayed out.. I finally got tired and per your advice I saw where the addons and extentions where kepted so I did a backup of my bookmarks.. and manually deleted all extentions and addons.. Hopefully this will fix the problem if not I will have to do a fresh install of mozilla.. Thanks again

I have the z 4.6.7.6 addon and I removed my profile and did a fresh install and it's still there. ***damn** this makes me rage...

moderator edited language - https://support.mozilla.com/en-US/kb/Forum+and+chat+rules+and+guidelines

Okay here's a fix:

type "about:support" in the address bar and look up the extension ID. Use it to locate the extension .dll file (For me that was C:\Program Files\Mozilla Firefox\Extensions\< Extension ID>\Componens\25f3e8c0.dll )

Open the .dll in Notepad and delete everything (and write some offensive words while you're at it), save it. The extension is now braindead, the thing installing it isn't aware that it doesn't work anymore so it leaves it unaltered.

I had this problem, too. I followed the advice from Slonimsky, but after I changed the .dll file, It was still in my extensions list. I went back and deleted the whole extension, which in my case was C:\Program Files\Mozilla Firefox\Extensions\{675eba94-03cf-5dda-6b53-ce37c7e7437c} . After I re-started Firefox, it was gone! Good Luck

Thanks! I'm not sure what this extension does or doesn't do. It's been listed there in my add-ons window for some months, having me worried. I feel that any extension that lacks a proper name and description should be discarded. I've removed the extension's entire folder from my computer.

Guys, I've done some research into this. By what it seems. it's part of a malicious keygen or crack, that has nested it self into the system. Because it's installed in an official manner, it's not seen as a virus/ad-ware and therefore isn't detected by conventional systems.

http://www.computerpartsgreenvillesc.com/dealing-with-the-z-4-6-7-7-firefox-extension/

To remove it, you could follow Slonimsky's guide. I don't know if this exploit works cross-platform, but I doubt it since it's part of an keygen/crack.

I had that problem too all i did was uninstall firefox delete the folder in the program files and reinstalled it and it was gone.

Thats because that is where the extension resides I found it there and just deleted the extension and was done with it

it is not, or should I say was not part of a keygen crack I installed a program I got from neowin and it installed the extension as well as other extensions and programs. And I'm not saying it is neowins' fault, they may not even know of this problem.