Reply #6: Agreed. Time to play some politics.

[IdaBriggs]

Start taking notes. Record comments, including days and times, including the comments she is making "trashing" the supervisor. Then, go to the supervisor, and explain how you don't think her saying these things to people like (and list the folks she's saying the stuff to) about the supervisor and the other employees is building a productive work environment. Quote from the notes you just HAPPEN to have brought with you, including the date and time. Explain VERY EARNESTLY that you don't like talking behind people's backs, but you are concerned that it is undermining the supervisor's authority when she says (bad thing about the supervisor), and isn't helping to maintain a productive team environment when she says (fill in the blank) about (whoever). Ask politely if they can talk to this woman about NOT being a trouble making gossip, and perhaps concentrating on her job, or, if she doesn't have enough to keep her busy, perhaps she could take over some of the grunt work that isn't being done?

I guarantee the problem will disappear quickly, with her either being fired, or correcting her behavior if she is incapable of stopping her stupidity. The key is YOUR handling the situation with credibility, and making sure the supervisor knows THEY are being bad mouthed. Your supervisor WILL NOT protect either you or your co-worker, but they will watch out for their own career, and someone going around saying "bad things" about them to other people is something that is a threat.

Enjoy!

ON EDIT: Do I have to clarify that you may need to help "encourage" her to say bad things about the supervisor, if she's not volunteering them on her own? This is from the "play to win" school of workplace politics, and should only be used when someone faces career problems because of a manipulative trouble maker....