On my Windows 8.1 64-bit laptop I switched from Zone Alarm to McAfee Total Protection a few months ago. Everything worked for the first month or so, then I started having problems running Act! 6. It would launch, but then just freeze, with the "hour-glass" just hanging there. I checked System Restore and found that the most recent change to my system was an update of the McAfee Vulnerability Scanner, which is part of McAfee Total Protection. So I turned off that component of McAfee Total Protection. No joy, Act! still would not run. So then I restored the system to just prior to that update of Vulnerability Scanner, and Act! ran fine.
After much analysis by McAfee support, it was concluded that I would continue to have the same problem every time there was an update to McAfee Vulnerability Scanner and I would have to do a system restore to get Act! running again. The solution: Uninstall McAfee entirely (probably should have McAfee support assist, to make sure everything is gone). Then reinstall without the McAfee Vulnerability Scanner component installed. With that configuration, the VS will not be updated, because it is not installed, and Act! 6 plugs along as the good trouper has always been!