Trouble with Leaving a Comment

I have had a few people email me to tell me they tried to leave a comment but were unable to. I have had comments from non-blogger people, so I am not sure if I have something that I need to change with the settings or if it is something that they need to do. Does anyone have any advice? I love hearing from people, so I want it to be easy to leave comments. This technical stuff is not "up my alley" so I am clueless. Please leave me a comment if you know what I need to do (and if you know what I need to do and can't leave a comment, please email me)