You should be asking Ancestry. There is nothing Firefox can do.

If you use the Search Firefox Help box above you'll find plenty of references to old versions of Firefox and the best way to go back,

You should look out for step by step instructions by the real experts like cor-el and TonyE. If you wait a little while they may post here directly.

I, for one, usually strongly discourage people from going back. Heaven forbid, but using IE(up to date I hope) for this particular purpose may be the best idea.

Nothing that Mozilla can do rather as it is not up to Mozilla to make third-party Extensions be compatible with Firefox. Mozilla often does try to work with the authors to try and speed things along though.

Firefox 4.0 came out March 22 so unless Ancestry authors are running into issues, they should have a update by now as even the slow Norton had a update for their toolbar for 4.0 (not proper one for 4.0.* though) a while back.

Sorry James, you certainly deserved a mention along with co-rel and TonyE.

Thanks so much for quickly replying to my question. I will contact Ancestry and hopefully they can help find the right solution. My last resort will be trying to go back to Firefox 3; I'm not sure that would be a good resolve or a smart move.