Script causing server to crash?

I got an email from a reader who had attempted to comment on my blog:

http://www.nixit.co.nz/wordpress/

The email said that the wouldbe commenter had had some error messages. I looked at the file and say that the permissions were incoreect. I tried to change them, overwrite the file etc and couldn’t. In desperation (feeling thick) I emailed my webhost and …

basically they say that the comments script is overloading their server.

The whole story is on my blog.

Could a kind soul look my problem and give me some advice about dealing with it.

TIA