I'm sure there have been threads about this in the past, but I couldn't find any using the search function.  I skimmed through a few of the old pages as well and couldn't find anything.

I have no trouble coming up with new ideas for books.  I've got one in particular that has been bouncing around my head for a couple of years.  In my head it's actually a pretty well developed world, but every time I sit down to write it, my brain *giggles* and runs away, and I'm stuck staring at a white screen.  If I force something out, I'm literally cringing as I write it.

I don't have any problems with short, nonfiction stuff.  Every paper I write gets an A, and usually a comment about me being an excellent writer.  And it only takes me a couple of hours to bang out a 10 page paper with minimal revisions.  But man, when I sit down to write a novel, I can't seem to do a thing.

So how do I get started?  Or better yet, how did you get started?  What do you do when developing a new idea into a full sized novel?