For the last 2-3 days, all my email notifications are taking me to the first post in the thread instead of the last .

I am not debugging anything like that this week because we've been experiencing a DoS attack all week long in addition to having to reboot the MySQL server a couple of times for various reasons. If the problem still exists after all of this is taken care of, I'll look into it at that time.

A clue: I thinkl the notification problem, the link history problem, and the problem with the "first unread post" arrow taking you to the same post on subsequent visits (even though new material is added) are all the same trouble.

On the subject of DoS attacks, I'm not sure if you're aware of this dani now?

But I was thinking the search engine function could be exploited. In the sense that non registered members, could acces the site from a proxy then query your database over and over again (program engineered), with no limit it would seem.

Other sites have captchas after each search for non-members?
What d'ya think?

With a dynamic site such as DaniWeb, there are a lot of pages that can succumb to just being constantly hit over and over again: viewing very large threads, the today's posts link, searches, member profiles, forums, etc. All of these pages take up server resources by having to sort through the giant posts and threads tables in the database. Unfortunately, it's just not feasable to add a CAPTCHA everytime you click any link throughout the site. However, a couple of precautions have been taken to ensure searches don't overwhelm the server. Firstly, there is a regulation in place that lets a single user do a search only once every 5 seconds. Something else that helps is, by default, we outsource our searches to Google. Therefore, we only have to be concerned with today's posts, posts since last visit, list of unanswered threads, etc.