XML issue

Hi,

I've noticed that in the Admin area of my WPMU 2.71 installation, when I go to Admin>Blogs and click the Edit,Delete, Archive,DeActivate, or Spam buttons for any of the blogs, I get an XML file displayed with this error:

This XML file does not appear to have any style information associated with it. The document tree is shown below.
-<playlist version="1">
?<trackList>
?<track>
<location>/wp-admin/wpmu-blogs.php</location>
<meta rel="type">image</meta>
<image>/wp-admin/wpmu-blogs.php</image>
</track>
</trackList>
</playlist>

Any ideas on this?