This issue is usually caused by a lack of the FSX Service Packs 1&2. Please note, if you own the Acceleration pack, it already includes SP1 and SP2.
Service Pack 1 and Service Pack 2
Please first try by downloading the service packs. If your PC tells you they are already installed, please do not attempt to install it again as you may corrupt your FSX installation.
You can download service packs 1&2 from here. Please note that you must install SP1 before SP2.
Acceleration Pack Users
If you are using the Acceleration expansion pack, please insert the Acceleration disk in your your PC and select 'Uninstall' from the list of options. After this process has been completed, please reinstall the Acceleration pack. You might need to take the disk out and put it back in again to start the process.
If none of these solutions resolved your issue, please create a new ticket and a dedicated member of our team will be able to assist you within 2 working days.