My Dilemma

I have nothing to do at work today. NOTHING. I "spring cleaned" my office on Friday and expected to be busy today because we had a client meeting scheduled for tomorrow. The client re-scheduled, so I have no work. I've asked all the partners in the office if they need anything and they "will let me know" if they do, but so far, nothing. Now, in my old job, I would've been very happy about this and probably taken half the day off. But here, I can't do that. First of all, I have a billable hour requirement (1180 hours to go), so I NEED work and not having work is a bad thing. Second, I just had my associate review last week during which I was criticized for only one thing - leaving at five. Now, I would like to note that I was NOT accused of not doing my work, or even of not being here when needed. In fact, the "criticism" said that I leave at 5, which has not been a problem...yet. In fact, continued my criticizer, I am always willing to stay late when needed and have never turned down work. Still, "consistently leaving at 5" apparently creates a perception that I am "not dedicated" to my job. Obviously, I think this is crap. I am often the first person in the office, so it makes sense that I am one of the first to leave. Also, I work at home in the evenings and on the weekends. I simply see no point in sitting here just for the sake of sitting here. But, alas, I have been told that "strategically" this is what I should do. So, I am trying to force myself to stay until 6 from now on, but when I have NOTHING to do that is kinda rough. Especially because, also unlike my old job, I can't watch TV in my office. Well, I can, but here I risk getting "caught." At my old job my boss would just be like "whatcha watching??" And then most likely tell me I don't get paid enough and I should just take the afternoon off. Here, watching TV in my office may just increase the "perception" that I don't care about my job. So, instead, I am blogging. Sooooo much better, don't you think??