I have a coworker who neglects to perform her work properly and often acts unprofessionally (has been reprimanded for both in the past). She's also developed a habit of napping on the job, which I'm pretty sure our manager is unaware of. On top of this she is argumentative and creates an uncomfortable environment; she seems to be acting hostile to me in particular. I can't tell if the manager doesn't address this because she feels it isn't a problem or not doing anything because she doesn't know. So, where's the line between keeping your head down or saying something, especially when you feel uncomfortable around this person?
She doesn't do her work correctly which means more work for everyone else on the team.
No it does not! That is unless your boss tells the rest of the team to pick up her slack and in that case, the boss knows she is a poor performer.
Feel free to tell her you're not doing her work, but possibly you could make an effort to help her if she starts behaving professionally. Then she can be the one to run to the boss, but wouldn't she look a little foolish?
I'd say talk to your boss about it, but either he isn't aware of the situation because the team covers for her and doesn't share here bad performance or the boss doesn't feel the need to do anything about it.
There is a difference between helping someone and enabling them.
Given the rate and direction she is going, it's only a matter of time before her job becomes history. If I were her boss, it wouldn't matter to me whether she screwed up doing her job or that someone else screwed up trying to do her job for her. Either way, she is accountable.
If she refuses to come to you for advice and feedback, it's her decision. If the result is substandard work, then it's an outcome for which she will either responsibility for or made to take responsibility for.
Does not perform her own duties. Does not work well with the staff and management. The handwriting is pretty much on the wall. Any complaint you make only hastens the logical outcome of her choices, actions, thinking and behavior.
Calling somebody over their professionalism is not your domain. Calling someone out someone over how their thinking, actions and behavior has impacted your work, and not for the better - that's totally appropriate. If you can describe how her thinking, actions and behavior affect your effectiveness on the job, then make your complaint ASAP.