RSS feed showing up as completely formatted pages??

Hi,

I have a custom theme, built originally with Artisteer, heavily modified, and for some reason the site.com/feed as well as feed/rss feed/rss2, etc., pages are coming up as one fully formatted page with all posts. Can’t figure out why it’s doing this. Help?

http://hillsboroughyarn.com/feed
http://hillsboroughyarn.com/feed/rss
http://hillsboroughyarn.com/feed/rss2

Permalinks are on, though there have been some issues with the mod_rewrite in the past.

My client’s customers want to get her blog feed and I can’t make it work. I’m stuck. Help?