A few people have written in to say they've received the email alerting them a new comment has been added, but when they click the link in the email to read the comment they just see "Page not found".
This happens when, as Admin user, I've deleted the comment before you've had a chance to see it. There are two reasons this might happen:
1. Spam
The most common is that a spammer has posted a comment advertising something. I delete these as soon as I see them.
2. Duplicate comments
Occasionally a user will submit the same comment twice. If I see this I delete the duplicate. (You'll be able to spot these as you'll receive two alert emails at almost the same time.)
It's annoying when it happens, but better to delete them than have you clicking on the spammer's links by mistake.
Regards, David