Ok. Thanks a lot. I guess that might delete the addons I already have but that's fine, I can get them back in.
Welcome to Simviation, Wild
It shouldn't delete anything....it will just restore any of the original files that are missing.
Do not uninstall FSX.....just run disc 1 and choose the repair option

Just in case though.....make a back-up of your main FSX folder

Chuck