Keep getting these errors when i try to make a post/topic on my site

[divinit3]

Every time i try to make a topic or post on my forum i get this message, please help.

 

[divinit3]

Bump

 

[ShadowedGrinner]

I get this error too, constantly.
Try giving the link to where you are at whenever you encounter the error.

 

[divinit3]

i get the error whenever i try to post a picture or "()" in the a topic and other specific keywords or symbols i think it has something to with the htaccess and i found on a website a code that lets me bypass the the error Example:

RewriteEngine on

<IfModule mod_rewrite.c>
RewriteBase /
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>

but even when i do that it doesn't save the new thread or post on my forum and just redirects it to my index, i hope this makes sense but yeah i really just need a code or something that lets it save on the forums after using one of those key symbols or an image.