Since I installed the Windows 8.1 preview (x64) tonight, FSX no longer starts. It's CTD 20 seconds into startup.
I'm starting to see some buzz on a few forums, including Microsoft's TechNet (?) forum and many have the exact same issue.
Just thought I'd throw this out there and maybe save some pain of cleaning out 8.1 ...
If you've upgraded already and are experience (or not) this issue, I'd love to compare system specs.