Creating additional single.php’s that work!

I have an iframe on index.php. The individual post page is then loaded into the iframe. I modified single.php so that it fits the iframe–no comments, no header/footer, just the navigation links and the permalink. So at this point, I can go back and forth between the posts, while staying on the home page of my blog!

However, nobody can comment now! What I want to do is to be able to, from the iframe, click on the permalink of a post go to the “full” version of the post page.

I’m having trouble doing this because I only have one single.php, which I stripped down for the iframe. This means that when the permalink is clicked, it just takes me to that stripped down post–without the comments section and all. I’ve tried creating an additional stripped-down template – iframe.php – and leave single.php alone, but iframe.php won’t load into the iframe– it just throws this error:

Fatal error: Call to undefined function: have_posts() in /home/ldrox/public_html/blog/wp-content/themes/default/index.php on line 1

Help!