Microsoft Flight simulator 2004

I haven't got FS2004, but does it need the CD/DVD disc to be in the PC to run?

If so there was an update issued that may be causing the problem - https://support.microsoft.com/en-us/help/3086255/ms15-097-description-of-the-security-update-for-the-graphics-component-in-windows-september-8,-2015

If this is the case see - https://answers.microsoft.com/en-us/windows/forum/windows_7-gaming/kb3086255-is-this-a-half-baked-solution-or-am-i/13d4c03e-f04f-40b9-b438-e903eda3cab9 for a work-around with a batch file, or remove the update. I was getting a similar sounding error for another old game in my case.

Also, If this is the case, then if you can find a 'No-CD' patch from a trusted reliable 3rd party source, then that would probably also work. That choice is yours, but as a very minimum fully scan any downloaded file with your updated AV program before running them, and test it and the download URL at www.virustotal.com as well, if possible. You can use VirusTotal to check the URL of your download site, and if the file is less than 128MB you can upload it to them to check the actual file as well. But as I say, the choice of using a No-CD patch is yours.

If it is not the above case, then find the FS2004 start up program file ( possibly called fs2004.exe - you will need to search your PC ), basically the file/icon you click to run the game, and then right-click that file and click 'Run As Administrator'. This assumes you are in a standard user account and not already using an Administrators account.

This article - https://www.sevenforums.com/tutorials/11841-run-administrator.html gives more detail.