WTF is this thing in Firefox?

[GagHalfrunt]

Just upgraded an old Firefox install to version 21.0, no other changes. And this annoying little box is now hovering over the file/edit menus in the upper left. Wasn't there before today, only appears when Firefox is open. So it's related to FF somehow. WTF is it and how do I make it go away? Won't respond to either left or right clicks and doesn't seem to be related to anything in the task manager.

System is Windows 7 64

 

[lxskllr]

Never seen it. Could it be warning about a plugin that needs to be updated?

 

[Jodell88]

Misplaced addon bar?

 

[FLegman]

Saved Passwords database corruption ?

 

[Lifted]

Thumbnail Zoom Plus Add-on

https://addons.mozilla.org/en-us/firefox/addon/thumbnail-zoom-plus/

Maybe it needs to be reinstalled or isn't compatible with the latest firefox udpate.

 

[GagHalfrunt]

Thumbnail Zoom Plus Add-on

https://addons.mozilla.org/en-us/firefox/addon/thumbnail-zoom-plus/

Maybe it needs to be reinstalled or isn't compatible with the latest firefox udpate.

Winner Winner Chicken Dinner!

Thanks.