According to the Knowledge Base article Q817606, it says the following: Patch Replacement Information This patch does not replace any other patches. 816073 isn't downloadable :/ The urlmon.dll file (6.0.2800.1226) in the August 2003 Cumulative IE6SP1 patch supercedes the version of urlmon.dll (6.0.2800.1216) in the IE6SP1 update released yesterday. I don't know what prompted Microsoft to release this, but this cannot be installed if the August Cumulative patch is installed. This hotfix list was created from a normal install of XP SP1 I ran yesterday, viewed on WindowsUpdate