Ensure the task scheduler service is running and configured for the proper account. Scheduled tasks maintains a generic log file in c:\windows\schedlgu.txt. Additionally, you open c:\windows\tasks and verify the status of the task.
For example a common result code, 0x653, means "Check server path". Make sure the double backslash (\\) is placed before the server name in the installation parameters field.
F-PROT Antivirus and Command Anti-Malware are products of CYREN