Thanks, Adrian.
I don't think we've had any experience, or feedback from users, with IBM Security Trusteer Rapport, I'm afraid (
http://www-03.ibm.com/software/products/en/trusteer-rapport ). Whether it does file-scanning, I'm not sure, although a brief read of IBM's website suggests to me that it might.
It would certainly be worth disabling it (or uninstalling it, if disabling it isn't possible) to check.
Some software that's installed on both your PCs (apart from Hauptwerk's installer) must be trying to access the file.
Although I have been quite happy with Avast, I will try replacing it on my laptop with, say AVG (any problems?).
I know quite a few Hauptwerk users do use AVG, and I don't think we've heard of any problems with it. We test with, and use, McAfee and Norton here.
Best regards, Martin.
Hauptwerk software designer/developer, Milan Digital Audio.