I had stalled on the Novel there for a while. I get writer's block the same way I get insomnia - suddenly, viciously, and fleetingly - and while it's annoying, it's nothing I can't get over given a little time.
I'd say I get off lightly. The Wikipedia article on writer's block suggests that people can suffer from it for years at a time, something that I can barely imagine even in my wildest dreams. It's usually a function of me getting a little fuzzy on the most important detail: What happens next?
I have my characters. I have a scene. I have imagined the bones of a storyline, so I know with reasonable certainty where they need to be and what they need to do. But something isn't quite working out right; I can't make the bridge that takes them from here to there, and thus the whole narrative screeches to a halt. The actors pause, the threads are frozen, and everything just stands around waiting until I can figure out what happens next.
I'm getting to the end of the second draft, so you'd expect that I shouldn't have these problems. But rewriting, changing, adding new elements, and other random literary effects have changed the story from the first draft, and a plot device that might have worked before is out of place now. Such is the way of writing, I suppose. It's always a process of refinement from the blobby story shapes you begin with.
I was trying to remember earlier what exactly inspired me to write the Novel. What was the first idea? The first concept or theme? Truth be told, I really don't know for sure. I play around with my ideas before ever committing them to text, and during that time they're in a constant state of flux - like Play-Doh, or something. You have your basic form, and you shape it and squash it and then mash it all up together again before starting over, and it takes many iterations before you're finally happy with it and ready to get to the serious business of making it presentable.
One thing I've noticed about the refinement business is when I'm having trouble with the Novel, the connection that finally breaks through my writer's block can literally come from anywhere. It's come from things I read online, things I see or do, and very frequently, my friends. Shanks (other talented writer friend) has always offered a lot of ridiculous suggestions, but he has his moments, and some of those have been worked into the Novel.
I'm sure someone will ask me at some stage, "Where do you get your ideas from?" So, while I'm on the subject, here's a list of some things that have given me story material or helped to break a block:
A certain well-known MMORPG that you will have heard of, unless you've been living under a rock for the last five years
"You should never start a story with what the weather is like."
A very, very old Batman novel
Shanks and Duri's weird comments on my work
An autobiography of a forensic scientist living in Rhodesia way back when
Single words or phrases, up to and including single words only three letters long
Imagination is a wonderful thing, and it can draw the threads of taleweaving from anywhere.