Yesterday Microsoft released KB971026 which is an update to the FCS Antimalware engine. This update installs successfully without issues. However, after this update is applied, the initial FCS Client package called " Client Update for Microsoft Forefront...

A catch-up scan is a scan that is initiated because a regularly scheduled Forefront Client Security antimalware scan was missed.  Usually these scheduled scans are missed because the computer was turned off at the scheduled time.  The FCS documentation...