I get a fatal error message when I open the menu in FSX. After initialization I tried to change views but no response. All my key assignments were gone. After re-asigning a couple key assignment I tried them with keyboard or saitek yoke, I get fatal error. I have no assignments and when I open to reasign I get fatal error after trying the assignments. I suspect its the FSUIPC program I just installed recently. This happen to anyone after this program was installed.

Check the fsuipc forum to make sure you have the latest version.

 

Try right-clicking fsx & select "run as administrator"

 

If neither of those helps try moving fsx.cfg to a temporary folder to make fsx build a new cfg file. Fsuipc has a similar file you can do the same thing with, I think it's called fsuipc.ini