While trying to put an RSS reading web part into my SharePoint 2007 site, I used a random feed from the Web and it worked fine. I then created my own feed and pointed the web part to it and now the web part no longer works. (Message: "An unexpected error occured processing your request. Check the logs for details and correct the problem." And no, I don't have access to any logs.)
My feed is valid, according to the W3C validator. The SP site is on an Intranet but both feeds come from the WWW with no password or auth needed so I'm pretty sure access isn't the problem. (Which was the most common suggestion I found when looking for an answer, both here and in Google.)
I've eliminated all the variables I can. The last variable is that the one I tested with was Atom and mine isn't. I'm guessing SP wants a certain flavor of RSS. Does anyone know what kind of feed SP 2007 wants? Or if the problem might be something else entirely?
Update: I guess "feed" is the proper generic term. Still, the SharePoint "RSS Viewer" (their term) works perfectly with the aforementioned Atom feed and not with my W3C-validated RSS feed.