Yes, I've been there. I think it is just general burn out, something that happens sometimes after one has been working very hard and/or under a lot of stress for a while. Once you get through that season, you need a rest and your body and subconscious mind know that, even if your conscious mind has other ideas and wishes you were being more productive. I have had this happen at times in my life. It's very frustrating because on the one hand I wish I was doing all these things, but I just don't have the motivation to do it, I just want to rest. I think the best thing to do if you feel this way is to give yourself permission to take it easy for a week, cut back on after work activities and then decide what day you will return to working on the thing you need to do.