Microsoft reissued 2 earlier updates today to address bugs in them.
MS13-057 ("Vulnerability in Windows Media Format Runtime Could Allow Remote Code Execution") was originally released in July to address a vulnerability in the Widows Media code in all supported versions of Windows that could allow code within a maliciously-crafted media file to execute. Later it was determined that the update could cause some WMV media files to fail to encode or decode.
On August 13, Microsoft re-released this update for users of Windows 7 and Windows Server 2008 R2. Today's re-issue of the update is for users of Windows XP, Windows Vista, Windows Server 2003 and Windows Server 2008.
MS13-061 ("Vulnerabilities in Microsoft Exchange Server Could Allow Remote Code Execution") was released in August to address vulnerabilities in the document viewing features of Exchange Outlook Web Access (OWA). It was quickly discovered that, on Exchange Server 2013, the update could cause the server to stop indexing. Microsoft withdrew the update and released a registry hack to work around the bug.
Today's release of the update fixes this problem. Both updates are available through the normal services.