To round this issue with Repair out and hopefully close it down.
1. I re-installed FSX + Acceleration, all was OK
2. I installed Sludge's Hornet and Dino Cattaneo's T-45. All was OK
3. I installed NOLF Choctaw and the associated programs FATAL ERROR.
4. As explained previously I had not run the Acceleration disk because I had not realised it was necessary since I have viewed Acceleration as an Add-on disc not a program disc. The "meat" of the FSX driver must surely be on discs 1 + 2. Following Virtuali's suggestion I ran Discs 1 and 2 followed by Acceleration. No improvement, so I am back to Fatal Error and so an un-install followed by full re-install.
I sat and watched the "Repair" process as reported on the screen - it seems to me all that happens is that only the original MS Aircraft, MS Sceneryand MS Weather files are overwritten i.e. the settings files and non MS Add on files are not touched. This could be explained by the fact that the additional files are not on the MS discs (i.e. they are generated by the PC's OS) so as far as the FSX program is concerned they don't exist.
What I find strange is that it seems the core FSX program files are not disturbed. As I have already found network settings etc are also (thankfully) not touched even on a full re-install - possibly because these new settings too, are "outside" the data on the FSX discs and so are ignored during Repair.
However, when I incorrectly installed the scenery I must have by mistake upset part of the "core" program which can only be re-set by a full re-install. I think that most Add-Ons have been written for XP but for the Win7 OS some "improvements" have been made which screw up the addition of "XP Add Ons".
Sorry if this is a bit long but there is little info on this subject. I have Googled "FSX Repair" which is not much help, "FSX Appcrash" is a little more help but not much.
If anyone knows how to re-set FSX (especially in Win 7) without a full re-install I would love to know it (and so would many others). Since MS is no longer supporting FSX there is not much hope of having an "Official Answer."
Tregarth
