User can not able to add comments

I am using wordpress version 3.0.1 & theme mistyLooks
The users can not able add comment i my blog post.

The Url Before Submitting Comment.
https://justrelaxme.info/2010/12/how-to-write-code-with-standards-in-c/#respond

When ever user enter comments it shows me empty page.
with the following url

https://justrelaxme.info/wp-comments-post.php

But I as a administrator can capable add comment on my post with out any problem. what is the problem.

Please Can any one help me on this.