Feedburner error

I’ve been trying to use Feedburner. And trying various plugins. But when someone clicks on my RSS Subscribe link they get a 404 error:

HTTP Error Code: 404

Detail: Invalid path /id=jd8elunftfcpd2jfudqckppjh4 was requested

I can’t figure out where that path is coming from. I can’t find it anywhere in any configuration page.