Of the 5 licenses of McAfee Internet Security Suite, only two computers had problems, both of those subsequently were repaired without needing to reinstall McAfee... It is possible of course this had nothing to do with McAfee updates. In both cases Windows security reported that it was unprotetcted by an antivirus program and firewall; McAfee probably was performing an update while a Windows event (such as shutdown, hibernate, etc.) was occuring and perhaps this interrupted the normal update process?
When Windows makes updates it displays a screen message during restart, "Windows Updates in progress. Do not power off computer." However, there is no such warning from McAfee.