After looking at their raw feed at http://finnern.com/future/rss.xml however, I don't see why this would be the case... but then again, the error message is so vague, it's hard to say what's going on really.
Anyone have an idea as to why LJ is choking on what appears to be a valid feed? Is there some kind of bug in how LJ is handling this feed, or is there something wrong with the feed itself that I'm overlooking?
Either way you look at it, it seems to point towards the need for more informative error messages on LJ so that problems with feeds can be diagnosed easier. It would be great if you could find out, for instance, that LJ is choking on the feed in a given location, as it could make it a lot easier to judge whether LJ is handling feeds in the correct manner.