NIS 2010 Fails to Remove Detected Threats

NIS 2010 detected two Downloader and six Trojan threats and indicated that removal failed for all of these in an "Action Required" screen that continues to appear.  The "ACTION" tab provides only "rescan" and "help".  I have run full system scans but the window continues to reappear.  Any advice on how to remove these viruses will be appreaciated..