RSS not working

It’s been called to my attention that my RSS feed is not working. I am thinking that it has never worked and I was unaware of it.

Here’s my address:
http://www.karensblog.com (which is a subdomain of my site) … the actual address is:
http://www.karenwinters.com/kblog

I have gone to feed validator and get messages that tell me something is wrong but I’m not a programmer so I haven’t tampered with the script. I’m hoping there’s just a setting wrong somewhere.

Validator tells me that feeds should not be served with the ‘foo’ media type, and that they are getting an unexpected MIME type … I am reading the validator explanation but I am clueless how to practically solve it.

I just did a basic installation and an upgrade to 1.5.2. I have added no plugins, so I don’t know what the problem is.

I notice that when I click on the RSS button in the url window that my feed takes this form:

feed://karenwinters.com/kblog/feed/atom/

But the feeds from most other people’s sites end in atom.xml
This was the same in 1.5.1 – it’s not an upgrade issue.

So I don’t know why my feed is different and apparently wrong for most newsreaders.
Help, please.