As the description suggests, it is recorded when F-Secure Internet Gatekeeper is unable to scan a particular file (thus potentially exposing the system to a threat). There are many reasons files can fail a scanning: corrupted files, encrypted archive files, files locked by other programs and so on. The administrator should identify the file specified and determine if it is a special file that maybe it should be excluded from scanning or if it is indeed a potential problem.
If file corruption is suspected, the administrator should run CHKDSk against that particular volume.
As a precaution, a full antivirus scan should be run, ideally using different antivirus solutions. Some users reported this after their system had been compromised (rootkits were found that were affecting the normal A/V scanning).
In many cases, this type of event is recorded as "The description for event ID(1) in source (F-Secure Gatekeeper) can not be found. The local computer may not have the necessary registry information or message DLL files to display messages from a remote computer. You may be able to use the /AUXSOURCE=flag to retrieve this description; see help and support for details. The following information is part of the event:<file for which the real-time scanning failure occurred>".