Running IIS 7 and WP 3.0.
I've got a web.config that has the necessary rewrite rules to make permalinks work, and they're working.
However, if I point to n-nexus.realtimepublishers.com/content/?feed=rss2, the server first generates an HTTP 404. Weirdly, it then delivers the RSS feed. The problem is that the initial 404 makes things like FeedBurner and Safari barf; Firefox displays the feed properly (you can see the 404 error in Live HTTP Headers, though).
What the heck am I not configuring properly?
UPDATE: Disabled all plugins. No change. Boo.