So my sister recently told me that she was having trouble leaving comments on my blog. I thought that it was a bit strange because I was still receiving comments, but thought that I'd do a little research. It turns out that for some reason, on some blogs, some people can't comment. To remedy the problem I switched my comment settings from being embedded in the post to opening in a pop up window. This seems to have fixed the problem.
I just thought that I'd share, because maybe you've had similar problems with your blog.