Need Avast to re-warn me about ''Rapport Cerberus''

[Tarq57]

That almost certainly means the file is no longer present.
The other possibility, and this is getting beyond my ability to help with, so I mention it only as a possibility (just in case) is that it is buried in the alternate data stream; ie: part of a rootkit.

That MBAM and Avast do not detect it would suggest this is probably  not the case.

What program is producing the message with the red cross?

[JC19483]

The red cross was just from Windows/my computer. I've also just ran Sophos and that came back fine

[Tarq57]

So that red cross was in response to a search? Or something else? It didn't just pop up there by itself.

[JC19483]

I clicked Start, then Search, yep.

[Tarq57]

All sounds good.
All the best.

[JC19483]

Thanks, very much, for your help, man