system
10
i had the same problem. i went to the the forum at FF and found a work-through. (hopefully FF or avast will come up with a fix, but in the meantime if you reinstall FF v 21 and change your settings in FF to NOT update automatically, then easypass toolbar will be back to how it should be!)
go here: FF v21 (US English) is available here:
http://ftp.mozilla.org/pub/mozilla.org/firefox/releases/21.0/win32/en-US/Firefox%20Setup%2021.0.exe