Error Code 4

Hi,

I am using this and I think its great. I am displaying my view as a feed.

The feed I am using is valid, and half the time when loading the view (or pressing update previes in the view editor), it works fine and as expected. The other half of the time, I get the following error:

Start tag expected, '<' not found on line 1. Error code: 4

And the view doesn't show any items. (only the heading stuff, EG:

<?xml version="1.0" encoding="utf-8" ?><rss version="2.0" xml:base="http://www.lolzroom.com/rss/importers/funnyjunk" xmlns:dc="http://purl.org/dc/elements/1.1/">
  <channel>
    <title></title>
    <link>http://www.lolzroom.com/rss/importers/funnyjunk</link>
    <description></description>
    <language>en</language>
          </channel>
</rss>

Any ideas whats causing this error, and how I can prevent it perhaps? If its a problem with the RSS feed perhaps running it through feedburner first might be an option?