Hmm, this is interesting - "64-bit Windows 2003 Server..." http://support.citrix.com/kb/entry!default.jspa?categoryID=524&entryID=6039&fromSearchPage=true "Internet Explorer in ICA Sessions on a 64-bit Windows 2003 Server Terminate With the Error, 'The application failed to initialize properly,' when Windows 2003, Service Pack 1 is Installed"