I can't duplicate your problem. I set Mozilla Firefox 2.0 as my default browser and used "Search on FamilySearch Internet", selected a person from the list of hits, viewed the person's data, and then used Firefox's Back arrow to choose the next person and view his data. No problem. I am wondering if there is a difference between the Mozilla browsers we are using. Mozilla Firefox 3 is expected sometime in 2008, maybe when you upgrade the problem will be solved.