I am also having a similar issue with the RSS Feed.
I have tried various fixes across the forums but none have resolved the issue.
Every time I try to add the RSS feed to any kind of site like Feedburner, Or if i use a validity checking service online for RSS Feeds I receive the same error, Server returned HTTP Error 404: Not Found.
But if i Copy and paste the contents of the generated RSS file and validate that, it claims it is a valid Feed.
Does anyone have a suggestion?