I upgraded Windows 8.1 to Windows 10 today following Parallel's KB article on doing so. No problems, only now I can't enter coherence mode and my display on a 27" iMac appears to be a 4:3 format with black space on both sides. Windows 10 says it's in Landscape so that's not the problem. Also, everything looks a little fuzzy and not at all like it did with 8.1. Here's a screenshot of what it looks like - http://take.ms/2hEtI