Yes I already have it installed on my other Mac, but it wont link with any existing trees, and I will have to make a new one to test that computer, but under instructions from help line, I had started a second tree on my main computer, and I found that exactly the same thing happened on that tree, spattering 10 plus copies of people etc after failed synchs.
I dont have anti virus on my Mac, and I had turned off firewall, again under instructions from Ancestry.
I wil try your suggestion at the end of your post when I return in a couple of days. Bye the way, I dont have any dross, games etc., my computer is a work machine for graphic design and photographic restoration in Photoshop.
I I will let you know what happens