WordPress SEO causes error in feed

The wordpress seo causes an error in my feed.

I’ve deactivated all my plugins to find the problem, and then activated them again, one by one. The WordPress Seo plugin seems to be the cause.

I’ve tried using an older version, up to 1.5.5. but every time I install and activate it, my feed gets this error:

The URL does not appear to reference a valid XML file. We encountered the following problem: Error on line 37: The reference to entity “subset” must end with the ‘;’ delimiter.

I’ve also tried deactivating all the other plugins and only activating the wordpress seo plugin. Still the same error.

Does anyone know how I can fix this, because I really want to keep using this plugin.

I’m at http://www.huisvlijt.com