Try running it in compatibility mode.
Right click the program executable, then click properties, then click the compatibility tab.
Here click Run this program in compatibility mode for: and select the version of Windows it was designed for.
(probably vista service pack 1) another option is to test selecting, Run this program as administrator. Click OK. test the game to see if it is running properly.
It sounds like he is having trouble getting FSX to install. So, he cannot run it in Compatibility mode if it is not installed.
Try running the setup.exe program on the disk as an Administrator.
You do this by going to file explorer and locate the DVD, On the DVD, locate the Setup.exe file. Right-click on the file and from the list, choose Run as Administrator.
From what I have heard and tried myself, this sometimes works. It appears that no matter how you launch Windows 7, you are never running as the Administrator. Security issues, I guess.
Anyway, I am having issues with Windows 7 and FSX also. I hope this helps you with your issue.