OK, I discovered the problem, quite by accident actually. I had the following statement in my .htaccess file:
PHP Code:
AddType application/x-httpd-php .php .php3 .php4 .phtml .js
That should have had .rss on the end of it. I don't remember why I thought I needed that statement in the first place, but after adding .rss to it, I got a parse error on line 1 for the .rss file, so I removed that line from my .htaccess altogether, and now all is right with the world again.
