How to Fix

So it appears that there are two different fixes. One of them completely removes FireShot, and the second leaves FireShot installed. Both appear to work.

Fix #1

Uninstall FireShot 0.31
Restart Firefox
Enter about:config in the address bar
Search for any variables that contain fireshot (I think this is the one that is causing the problem: general.useragent.extra.fireshot)
Right click on each one, and select reset
If you want, re-install FireShot version 0.25

Fix #2

Open the FireShot preferences
Uncheck Add information about FireShot into user-agent string
Restart Firefox

So a couple of my Firefox add-ons had updates this morning. I installed them all without even thinking about it, and my co-worker Adrian asked why I added the green background to my sIFR headings. I had no idea what he was talking about. He said he also had a Firefox add-on that was updated, FireShot.

I checked in Firefox on the Mac, IE, and another co-worker's Firefox on PC, and none of them had the green backgrounds. I disabled JavaScript, and the green backgrounds went away. So something is going on with my sIFR headings. Weird.

Anyone else seeing the green backgrounds? Anyone know why?

Weird Green Background in Firefox