One thing I've found helpful on E is to start writing their response to the one you're stuck on. How do they react to whatever it is you're struggling to convey? I find that helps you think about your actions and words from another perspective which is sometimes all it takes.
I usually do what Nic (and others) suggested - do anything but the thing that gives me the block. I read, I watch movies/TV shows, draw or paint... go for a walk or spend time with the little rascals (my nieces and my nephew) - clean my head, in a way. I find that I can only write if I'm on a happy-ish wave; I need to be positive for me to have the creativity, so I try to create that if it's not there.
However, I found that advice from Kythia awesome!

I'll try that. After all, you usually do have a general sense of direction where you want to go. I feel that this could help along those not-so-smooth flowing points. Thanks.

I found a very... unconventional way of getting over it. I had my daughter think up the premise for a story, and then I started writing it... now she wants it as her bedtime story
Yayness for kid and daddy time!

And if she can rid you of the block, more power to her.
