I seem to run into this problem kind of regularly...there are days when I'll get maybe a few hours of studying in but then run into a massive wall that makes me mostly unproductive for the rest of the day. I'll keep my laptop open with lecture material on it, but it's really just there to make me feel like I'm studying when I'm really not. I'm not exactly enjoying not studying, though, because I know I need to be hitting up the lecture material, but I can't really get on track and make myself absorb anymore of the really boring material. Anyone else ever run into this problem?