dmex, thx for your reply. The thing is, I seem to have sorted the problem.
Firstly, I've disabled my personal downloads folder in ZA's target scanning settings, uninstalled Process Hacker using Revo's uninstaller, did a reboot and reinstalled Process Hacker as Administrator. Now Process Hacker is loaded and sitting in the system tray and ZA is not hassling it. Unfortunately ZA cleared its quarantine and I cannot give you any screenshot. The entry in the quarantine was as follows, "not a virus" plus the apps install folder, but nothing more.
I looked in Process Hacker' folder at the exe file and found that it had been rendered useless. This was before I managed to uninstall it. I'll keep you updated should it happen again. Though I think install it as Admin may have overcome the problem. Could it be that the name of Process Hacker has misled ZA in to taking it as that. I can't see that been the case, MS's Defender [though not the best] did not have an issue with Process Hacker.