whats with mt-comment.cgi.? my server crashes when several scripts are actively being use by my few users. this is an old user who has been with us for 3 years and is just now that this thing is happening.
If they are running an old version of MT then it may have no defense against spammers and in fact that mt-comments is being targeted by comment spammers. An old solution was to rename the file but this would make things worse if you end up using a server side solution for this.
If you can detect bots and successfully omit google, inktomi and general good bots then the other ones in my opinion can be blocked.
With an rfc1413 lookup you can quickly say if the bot a search engine one or an advertiser.
If it's a problem related only to one customer then an upgrade on their blog software may also help to some degree.