The event was logged because our scanner service (mcshield) received an invalid file name to scan.
As you can see from the details of the event, there is no filename or "Received name". Somehow our file system filter driver got to place where it told our scanner "Hey Mcshield, scan [nothing] please"... to which Mcshield responds "Huh? I'm telling on you.... [Log event 5028]".
This is an error scenario we have catered for since we know it's a plausible logical outcome in handling file I/O. But unfortunately we can't capture enough contextual information about the occurrence to tell you "Why" it occurred.
If you have a system or systems that can reproduce this, I suggest working with the McAfee Support team to see if we can delve into this further and get that contextual info that's missing, to help us understand why it's occurring for you. Past efforts in other field reports have been inconclusve because of the rarity and unpredictability of it - but based on past attempts to investigate, you could check if you have the option to scan processes on enable turned on? We recommend it not be enabled unless you've configured the product for "maximum security".