False Starts

So, I'm sitting here at the Job of Doom, finished for the night and I decide to take a stab at writing. I've had this idea stuck in my head for a little while and thought now would be the perfect opportunity to exorcise it.
Didn't happen.
All I've managed to do is make a lot of false starts and get so disgusted with myself that I don't even want to look at the keyboard again.
Don't you just hate it when that happens?