The commercial software “File Joiner”, intended for packing a program and it’s required files and modules into a single file, is detected as a Trogan-Gen - I presume Trojan Generation or Generator. While it’s true that software like this could be used to bundle a trojan into an EXE, it’s hardly fair to mark the software and any file that it creates as a possible Trojan. Even the demo version, which can’t even create the resulting file, is identified as a Trojan-Gen.
Perhaps unwanted possibly malicious or some such is a proper category for this.
Not generator - The avast Win32:Trojan-gen is generic signature (the -gen at the end of the malware name), so that is trying to catch multiple variants of the same type of malware and is a fine balance between detecting a new variant and detecting something valid as infected.
You could also check the offending/suspect file at: VirusTotal - Multi engine on-line virus scanner and report the findings here the URL in the Address bar of the VT results page. You can’t do this with the file securely in the chest, you need to extract it to a temporary (not original) location first, see below.
Create a folder called Suspect in the [b]C:[/b] drive. Now exclude that folder in the File System Shield, Expert Settings, Exclusions, Add, type (or copy and paste) C:\Suspect*
That will stop the File System Shield scanning any file you put in that folder.
If only GData and avast detect it - GData uses avast as one of its two scanners so counts as 1 detection and almost certainly an FP.
Send the sample to avast as a False Positive:
Open the chest and right click on the file and select ‘Submit to virus lab…’ complete the form and submit, the file will be uploaded during the next update.