Pagination link on home page ("Older Entries") is broken

We're using Ata 3.5.1 on Wordpress 2.9.0. At the bottom of the posts on the home page of the website (www.maplegroveunitedchurch.org) the Older Entries link is broken.

This is what the href says: "http://www.maplegroveunitedchurch.org/index.php/Index.php/page/2" -- note that second "Index.php", with its odd uppercase I. Where is that coming from?

Needless to say, all we get when we click on this is a "cannot be found" error message.

Any help fixing this would be greatly appreciated!!