2 words causing Forbidden error

After typing a blog posting and submitting, I was faced with the following error:

Forbidden
You don’t have permission to access /wp-admin/post.php on this server.

Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.

So at first I thought my server was broken and decided to try again the next day. However, same error. Then I tried to post with a different text, and hey! It works!

So I went back and tried to re-post the unsuccessful post.

Same error.

I decided to post paragraph by paragraph. So far no error.
Then the error popped out at this paragraph. So I further isolated the paragraph to individual sentences and finally I found 2 words, when placed together, gave me that error.
They are:
“fetch him”

Amazing and amusing isn’t it.
Initially I thought it was my anti spam protection plugins . But even after I disabled Spam Karma 2, it still didn’t work.

I tried posting posts containing just “fetch” – works
I tried “him” – works
“fetched him” – works
just not “fetch him”.

You can’t even enter this 2 words into my wordspew shoutbox. It causes the same error but it doesnt show up, because of the AJAX thing I think.

Anyone can help me?

Thanks
https://aimevous.kewt.net