I often have issues when trying to "merge" results into a person (see screenshot)http://trees.ancestry.com/pt/MergeFamily2.aspx?ssrc
In the html source I see reference to an error page (not sure if that's always there and it's just shown/hidden when necessary).
This happens to me on a regular basis: Chrome (Mac), Safari(Mac), Firefox(Windows). Clearing cookies does nothing. To me this is an ancestry.com issue and wish it would be resolved as it has happened frequently over the last month.