Problem scenario
You have a website powered by WordPress. You see a big gulf of space between your widgets/ads and your posting previews. It only happens on one page of previews (not other pages). The ads are too far to the right when the preview doesn't wrap. Why are your previews not wrapping on one page?
Solution
The problem may be one posting. Change the postings (e.g., dates or categories), so they appear on different pages. You may need to have fewer articles on a given page to narrow it down. Once you determine (isolate and identify) the posting that is causing the problem, modify that posting. The previews it is among will not wrap with the problem posting. Sometimes republishing the problem posting will eliminate the problem. Alternatively you could republish every posting on the preview page that has the problem.