blank screen after post wp-comments-post.php

When visiting a blog and commenting, what does it mean when you are redirected to a white page wp-comments-post.php
We have been visiting other wp blogs that posted on our site and reciprocating over the past several weeks and now when we post we get a white screen with no message. Are we being blocked or considered spam? We have not spammed and only contributed to blogs that we felt we could contribute relevant responses too. Would appreciate any help with this. thank you.