This issue has been resolved.
The IT Help desk has received several calls about Trend Micro clients not working properly on Windows computers. In each case, the Trend Micro a red "No" symbol over it. The second icon in the Smart Scan Icons section of this Trend Micro article matches the icon: http://docs.trendmicro.com/all/ent/officescan/v10.6/en-us/osce_10.6_olhsrv/ohelp/clients/clicons.htm. This indicates that Real-Time Scan is disabled, but the KSU client does not seem to have an option to enable the scan anywhere in the console or in the icon right-click menu.
All the problem clients found so far are connected to the KSU-OS04.ads.ksu.edu server, and they have the 11.0.1050 Service Pack 1 update installed.