I have just acquired 8.1 Pro & cannot get very far in FS Deluxe. The program keeps crashing, usually when I press the alt key. Was just able to fly a pre-installed mission but when I go to free flight it gets as far as setting up airplane, airport, weather but then crashes with a fatal error.
It all worked well with windows 7...there's no going back though!
Getting very frustrated.
Windows 8.1 Pro 3.3 GHz 64Bit. 8GB RAM