The update recover msoe.dll file to its Windows 7 original. Re-install Windows Mail or re-copy msoe.dll of Vista and everything is OK.
re-copying msoe.dll or de-installing KB978542 leaves WinMail unprotected! How to repair Windows Mail after the installation of Security Update KB978542 on a Windows 7 system: bleepingcomputer.com//blogs//mowgreen//index.php?showentry=1684