use KB973688 from the microsoft site. It supersedes the above fix and actually solves the "problem". My office worked with Microsoft tech support a long time and thought we had fixed the problem many times, but it kept returning. In fact, keep ahold of the above hotfix because I needed to use it again when updating AC, but it is relatively painless to install. I suspect AC has an older version of Msxml that it installs on some win XP machines as my one Vista (boo) machine was not plagued by this problem.
