Slashdot | Netscape Says No RSS 0.91 For You The problem here is that the RSS format was written in XML and used a DTD (document type definition) that was stored on the Netscape servers. Whenever *someone* *somewhere* tries to parse a RSS file the Netscape server is queried for the file and the RSS file is validated against it. So now that Netscape removed the file people don't get to see the RSS summary but get an error instead.

What could be done is putting a copy of the file on an alternate location and changing all RSS files to match the new URI... well, this could be done if it weren't for the fact that Netscape copyrighted the RSS DTD... the only sollution left is to change to the updated RSS format which doesn't depend on Netscape.
http://slashdot.org/articles/01/04/28/2119211.shtm