Try turning dynamic off on the main page weblog:entries query, then put url_title={segment_3}. This basically tells EE not to figure out which page should be showing from the URL on its own, you’re instead manually telling it which article to show based on the URL. Also, make sure pagination is disabled on that particular query.
Basically, EE gets confused when there are multiple dynamic elements on a page that rely on URL segments, and it’s still a problem in EE2. You can see it in action on your homepage where you have two paginated queries, but if you go to the second page on one of them, both of them move to the second page. If what I suggested above doesn’t work, you may be out of luck. It may be worth posting a feature suggestion, a way to work around having multiple dynamic queries in one template.