Try repairing Internet Explorer.  For details see MS KB 194177 - "Description
of the Internet Explorer Repair Tool"
(http://support.microsoft.com?kbid=194177).  Note that recent cumulative
updates may have replaced the Microsoft Internet Explorer entry in Add/Remove
with one that reads something like Internet Explorer Q?????? in which case
uninstall the cumulative update, then run the repair and after which you
should reinstall the latest cumulative update.