immobilised by apathy

Apparently it's worse than I thought... I typed the title for this post about 2 and a half hours ago and since then I've just wasted my time on crappy flash games, just as I've wasted the whole of this week so far in the lab. I hadn't even noticed I'd gone so long without posting here until someone asked where I was. I feel like I'm in a state of suspended animation. I just move between the lab and my bed, without thinking or doing anything other than eat and use my laptop.
I've been using the fiction, leftover from similar behaviour during my honours year, that as a student, I'm only really messing up my own work and it's not like I'm an actual employee, to keep the guilt somewhat at bay. Today, though, I realised that, unlike at home, where I was paying tuition to do research, I'm costing my advisor more than a technician... Plus, I remembered someone saying that the success of an assistant professor really depends on their first grad students doing good work. So, now I feel extra guilty.
I don't know what's wrong with me. I mostly haven't been feeling so miserable and depressed. I just hit an immediate wall of resistance every time I so much as think about doing something other than reading blogs or playing games. I'm not sure I can blame this on the depression.
When I was doing honours, I spent a very significant portion of my time in the lab on IRC. I managed to restrain myself from slacking off quite so much for the short period of time I was actually getting paid well and while I was doing rotations I was better about working while I was in the lab, but I was only in the lab for shorter periods of time between classes. In any case, it's not like this is a momentary aberration in my usual productivity. This is just a slightly more extreme version of my usual slackness.
I started reading a book on procrastination last night (that I'd already renewed from the library twice without even opening) and it offers several possible motivations. I was nodding in recognition at all of them - fear of failure, fear of success, fear of losing autonomy, fear of separation, fear of attachment... I still felt like I have no excuse, though, because I don't have a clear reason or origin for my fears, like all the example people did. I can't even figure out what I'm actually scared of that's keeping me from doing anything.