Error when attempting comments

Thank you for taking an interest in my comment issue! All was working then out of the blue I get this error when trying to post a comment (no changes have been made on the back end):

Warning: Unknown: failed to open stream: Permission denied in Unknown on line 0 Fatal error: Unknown: Failed opening required ‘/usr/local/pem/vhosts/103592/webspace/siteapps/2106/htdocs/wp-comments-post.php’ (include_path=’.:/usr/libexec/php4-cgi/share/pear’) in Unknown on line 0

I am not sure if I should attempt to edit wp-comments-post.php and why this would happen. Any help would be appreciated. Thank you for taking the time to look at my issue.