What can I do about nasty comments in student evaluations that could cause me to get fired? I recently received the results of student evaluations. After my colleague (who is qualified to make such determinations) observed one of my lectures and said it went very well, a small group of students took it upon themselves to make some very personal, hurtful, and untruthful comments about me and my teaching. 

Unfortunately, it is quite a small class and only one other student did the evaluation this year so it looks really bad with all the negative comments and ratings. The place where I work has decided to take no notice of the comments from the lecture observation, nor to the fact that most of the students' comments are easily refutable based on videos that are made of each lecture. They are planning to fire me, despite my having ok (though not perfect) student evaluations in the past.

I personally think it is ridiculous to give student comments such a high importance and ignore anything else, because students often give ratings based on how much homework they get and how easy they think the exam is going to be. One student in the past commented that he had learned a lot in my course, and then proceeded to give me the lowest numerical ratings possible.

Do I have any recourse here? If nobody at my institution will look at the videos to see that the statements made by the students are false, can I make a claim for wrongful dismissal? Can the students be held responsible for their lies? The questonnaires are anonymous but they were done online so it would be possible for the institution to find out the identities of the students.

Thanks.

Update: 

Thank you very much for your replies.

This has gone all the way to the point where I have a meeting soon where I'm going to be told whether the head of the department intends to terminate my employment. 

At my request, an investigation was done into my allegation that a colleague had influenced my students' opinions against me, but the evidence I presented (emails from that person from before the questionnaires were distributed matching very closely some of the students' comments, the notes from the lecture observation, and videos of my lectures, not to mention my own written and verbal testimony) were not only ignored, but it was claimed that I had provided "no evidence" for my allegation. 

I have just found a video of a lecture given by my colleague in which he is seen and heard to completely trash me and make fun of me in a conversation with my students before his lecture begins. I look forward to presenting this at the upcoming meeting. 

Does anyone have any predictions for the outcome of this? Will this new video be considered or will they just ignore it as well and fire me anyway?

Thanks again.
To answer this question: "Can the students be held responsible for their lies? The questonnaires are anonymous but they were done online so it would be possible for the institution to find out the identities of the students."

Probably not.  If the university promised the students their comments were anonymous, then it probably cannot reveal their identities, which would rule out holding them responsible.  Most likely the university did not retain records of who wrote which comments, so as to protect itself against accidental disclosure or subpoenas seeking to deanonymize the comments.