Microsoft is backtracking on an update released earlier this month, after they discovered that a patch was released with a severe flaw. Users of Office 2003 had the option of installing a patch to fix several security vulnerabilities, and one of the patches in particular, MS08-051, was incomplete. It didn't encompass the entire set of vulnerabilities, letting the system (and user) believe they were up to date when in fact they weren't.
Microsoft has since rolled back the patch, and reminded users that people making use of Windows Update didn't have to worry about anything - only manual downloads were affected. For those that did install the security update manually, via the downloadable hotfix, the patch must be first uninstalled and then reapplied with the correct version.