I am currently running Windows 8.1 and have been for some time. I haven't tried to calibrate my set in some time. Possibly 6-8 months. The version of HCFR I was using back then worked perfectly on the same computer and same TV. Since my last calibration I had to do a clean install of windows 8.1 and about 2 days ago reinstalled HCFR to the latest version. I'm not sure what could have changed between the version 6-8 months ago and now but I would imagine that is where the problem lies. If I can figure out where to download old versions I can download them all and test them and let you know where the issue first began. I wish I would have paid better attention to the versions I was using but everything was running smooth so there wasn't a need to monitor version haha. Anything I can do to help out let me know and when I have time I'll be happy to check it out and get back with you.
Always destroying exergy!