This feed: http://www.essentialpim.com/forum/rss.php?f=3&t=5342 gives me the same old messages over and over when I click refresh. I mean: I refresh it for the first time, it shows all messages in it as new; then I right-click and select "Mark All Read", the messages are not bold anymore, as it should be; but if I click refresh again it shows me the already seen messages as new. Feed validaator says it's a valid feed: http://feedvalidator.org/check.cgi?url=http%3A%2F%2Fwww.essentialpim.com%2Fforum%2Frss.php%3Ff%3D3%26t%3D5342

The feed is syntactically correct, but the content it's generating is broken.

If you look at the XML data in the feed displayed on the feed validator page, you should see an element with the name guid. The value looks something like this:

http://www.essentialpim.com/forum/./viewtopic.php?p=22501&sid=SOME_LONG_STRING_OF_DIGITS

The guid is what feed readers use to tell whether an item is new or not. Two entries with the same guid will be considered duplicates. An entry with a guid that has never been seen before, will be considered a new message.

Now take note of the guid in that feed - cut and paste it into notepad or something. Then refresh the feed validator page and look at it again. You should see that the part on the end, after the sid=, will have changed. That's a bug - that should never happen. And that's why it appears to Snarfer as if it's a new message.