Thanks for the reply. I was thinking along the same lines - my first assumption is that it’s a false positive. Having said that, the scan I’m currently running on backups of that Mac laptop using the trial of Avast for Mac has found Trojans including the one reported here. I’ve also used VMWare Fusion to create a new vital machine having scanned my Windows XP disc, and I’m able to run this without any reports of infections (after installing Avast Internet Security Trial). Fortunately the affected virtual machine is configured to be isolated from the network, has no email accounts set up, and is only used for testing a web site with Internet Explorer. Therefore the risk of spreading something is presumably minimal - but equally the whole machine can be trashed with minimal consequences.

Either way something isn’t working right - given that Avast! Internet Security finds nothing on a disk scan or boot scan within the virtual machine, and Avast! free Antivirus for Mac beta doesn’t find anything scanning the virtual machines files on the Mac laptop.

Presumably whether it’s a genuine trojan or a false positive - one or other version of Avast isn’t detecting something properly?