Warning: Writer's Block Lane is a Dead End

Once again, I find myself digging my heels in. I've had a blank document page open all day yesterday, and it was waiting for me today. Normally having a blank page on my computer irks me enough to get my ass into gear and start writing. Yesterday (and today seems to be following the same trend) I just stared at it. There's nothing I've done that could get me to write.

Oh, I've hit the wall hard. The problem is I don't even know why.

It could be the characters. But I switched the casting around a bit and was really excited to bring back a character I haven't written with for four years. His personality works better for what I'm planning, anyway. I still didn't write anything. I decided not to do some renaming, which made me feel better because I like the names my characters have. Nope. Nothing. Na-da.

What the hell is my problem?

Maybe it's not this chapter that's the problem at all. Maybe I did such a good job with the last chapter that I have no clue how to keep things going, how to match it and surpass it. Maybe what I have planned isn't what needs to happen here. Maybe my characters are resisting because they see something I haven't, but can't speak loudly enough for me to hear them through the block that's gotten built between us. I don't know, and that's the biggest problem.

So let me ask you this: What's the worst writer's block you've ever encountered, and how to get you get around it? I feel like I'm shooting fish in the barrel... and missing every mark.