I had the same problems after SU13 - the sim froze while loading, usually at 90% completion (rough guess according to how advanced the blue line was when it froze).
I could usually use Task Manager to kill FS.exe, but there were days when this happened repeatedly, 3 - 4 times in a row, until I gave up trying.
My solution: I worked thru many of the troubleshooting tips for slow loading and CTD/freezes during loading, and that helped. For the last 3 days, I have been able to start the sim normally, and I had uneventful flights (uneventful as in: normal, without CTD). Here is what I did:
Open Windows Defender and turn off real-time protection.
- In the Cortana search box, type “Windows Security”
- Open “Windows Security” > “Virus & Threat protection” > “Manage settings”
- Disable “Real-time protection”
Good luck and happy flying!